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Rule2024-28707

Federal Motor Vehicle Safety Standards; FMVSS No. 305a Electric-Powered Vehicles: Electric Powertrain Integrity Global Technical Regulation No. 20 Incorporation by Reference

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Published

December 20, 2024

Effective

February 18, 2025

Issuing agencies

Transportation DepartmentNational Highway Traffic Safety Administration

Abstract

Consistent with a Global Technical Regulation on electric vehicle safety, NHTSA is establishing Federal Motor Vehicle Safety Standard (FMVSS) No. 305a to replace FMVSS No. 305, "Electric-powered vehicles: Electrolyte spillage and electrical shock protection." Among other improvements, FMVSS No. 305a applies to light and heavy vehicles and includes performance requirements for the propulsion battery. NHTSA is also establishing a new regulation, part 561, "Documentation for Electric-powered Vehicles," that requires manufacturers to compile risk mitigation documentation and to submit standardized emergency response information to assist first and second responders handling electric vehicles.

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[Federal Register Volume 89, Number 245 (Friday, December 20, 2024)]
[Rules and Regulations]
[Pages 104318-104365]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2024-28707]

[[Page 104317]]

Vol. 89

Friday,

No. 245

December 20, 2024

Part II

Department of Transportation

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National Highway Traffic Safety Administration

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49 CFR Parts 561 and 571

Federal Motor Vehicle Safety Standards; FMVSS No. 305a Electric-Powered
Vehicles: Electric Powertrain Integrity Global Technical Regulation No.
20 Incorporation by Reference; Final Rule

Federal Register / Vol. 89 , No. 245 / Friday, December 20, 2024 /
Rules and Regulations

[[Page 104318]]

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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Parts 561 and 571

[Docket No. NHTSA-2024-0091]
RIN 2127-AM43

Federal Motor Vehicle Safety Standards; FMVSS No. 305a Electric-
Powered Vehicles: Electric Powertrain Integrity Global Technical
Regulation No. 20 Incorporation by Reference

AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation (DOT).

ACTION: Final rule.

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SUMMARY: Consistent with a Global Technical Regulation on electric
vehicle safety, NHTSA is establishing Federal Motor Vehicle Safety
Standard (FMVSS) No. 305a to replace FMVSS No. 305, ``Electric-powered
vehicles: Electrolyte spillage and electrical shock protection.'' Among
other improvements, FMVSS No. 305a applies to light and heavy vehicles
and includes performance requirements for the propulsion battery. NHTSA
is also establishing a new regulation, part 561, ``Documentation for
Electric-powered Vehicles,'' that requires manufacturers to compile
risk mitigation documentation and to submit standardized emergency
response information to assist first and second responders handling
electric vehicles.

DATES:
Effective date: This final rule is effective February 18, 2025.
IBR date: The incorporation by reference of certain publications
listed in the rule is approved by the Director of the Federal Register
as of February 18, 2025.
Compliance dates: The compliance date is December 22, 2025, for the
emergency response documentation requirements. For all other
requirements, the compliance date is September 1, 2027, for vehicles
with a gross vehicle weight rating of 4,536 kilograms (kg) or less and
September 1, 2028, for vehicles with a gross vehicle weight rating over
4,536 kg. Small-volume manufacturers, final-stage manufacturers, and
alterers are provided an additional year to comply with the
requirements beyond the dates identified above. Optional early
compliance is permitted.
Petitions for Reconsideration: Petitions for reconsideration of
this final rule must be received no later than February 3, 2025.

ADDRESSES: Petitions for reconsideration of this final rule must refer
to the docket and notice number set forth above and be submitted to the
Administrator, National Highway Traffic Safety Administration, 1200 New
Jersey Avenue SE, West Building, Washington, DC 20590. All petitions
received will be posted without change to <a href="http://www.regulations.gov">http://www.regulations.gov</a>,
including any personal information provided.
Confidential Business Information: If you wish to submit any
information under a claim of confidentiality, you should submit your
complete submission, including the information you claim to be
confidential business information, to the Chief Counsel, NHTSA, at the
address given under FOR FURTHER INFORMATION CONTACT. In addition, you
should submit a copy, from which you have deleted the claimed
confidential business information, to Docket Management at the address
given above. When you send a submission containing information claimed
to be confidential business information, you should include a cover
letter setting forth the information specified in our confidential
business information regulation (49 CFR part 512). Please see further
information in the Regulatory Notices and Analyses section of this
preamble.
Privacy Act: The petition will be placed in the docket. Anyone is
able to search the electronic form of all submissions to any of our
dockets by the name of the individual submitting the submission (or
signing the comment, if submitted on behalf of an association,
business, labor union, etc.). You may review DOT's complete Privacy Act
Statement in the Federal Register published on April 11, 2000 (Volume
65, Number 70; Pages 19477-78) or you may visit <a href="https://www.transportation.gov/individuals/privacy/privacy-act-system-records-notices">https://www.transportation.gov/individuals/privacy/privacy-act-system-records-notices</a>.
Docket: For access to the docket to read background documents or
comments received, go to <a href="https://www.regulations.gov">https://www.regulations.gov</a> at any time or to
1200 New Jersey Avenue SE, West Building, Room W12-140, Washington, DC
20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. Telephone: (202) 366-9826.

FOR FURTHER INFORMATION CONTACT: For technical issues, you may contact
Ms. Lina Valivullah, Office of Crashworthiness Standards; Telephone:
(202) 366-8786; Email: <a href="/cdn-cgi/l/email-protection#3874515659166e5954514e4d54545950785c574c165f574e">[email&#160;protected]</a>; Facsimile: (202) 493-
2739. For legal issues, you may contact Ms. K. Helena Sung, Office of
Chief Counsel; Telephone: (202) 366-2992; Email: <a href="/cdn-cgi/l/email-protection#377f525b52595619644259507753584319505841">[email&#160;protected]</a>;
Facsimile: (202) 366-3820. The mailing address of these officials is:
National Highway Traffic Safety Administration, 1200 New Jersey Avenue,
SE, Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary
II. Background
a. Overview of FMVSS No. 305
b. Overview of GTR No. 20
c. Statutory Authority
d. Overview of the Final Rule Requirements
e. Changes From the NPRM to the Final Rule
III. Summary of Comments
IV. Response to Comments on Proposed Requirements
a. Expanding Applicability of FMVSS No. 305a to Heavy Vehicles
1. Normal Vehicle Operations and Requirements for the REESS
2. Post-Crash Safety for Heavy School Buses
3. Post-Crash Safety for Other Heavy Vehicles
b. General Specifications Relating to Crash Testing
1. Low Energy Option for Capacitors
2. Assessing Fire or Explosion in Vehicle Post-Crash Test
3. Assessing Post-Crash Voltage Measurements
4. Electrolyte Leakage
c. Vehicle Controls for Safe REESS Operation
1. Vehicle- and Component-Level Testing
2. State of Charge (SOC)
3. Breakout Harness Location
4. Over-Temperature Test
5. Overcurrent Protection
6. Venting and Visual Inspection
d. Mitigating Risk of Thermal Propagation Due to Internal Short
Within a Single Cell in the REESS
e. Thermal Event Warning
f. Vehicle Control Malfunction Warning
g. Protection Against Water Exposure
h. Miscellaneous GTR No. 20 Provisions Not Proposed
1. Vibration and Thermal Shock and Cycling
2. Fire Resistance
3. Low State of Charge
i. Low-Speed Vehicles
j. Emergency Response Information
k. Documentation Requirements
l. Compliance Dates
V. Response to Comments on Issues Not Discussed in the NPRM
a. Future Battery Chemistries
b. Marking and Labeling
c. Test Laboratories
d. Other Electrical Specifications
e. Static Rollover
VI. Rulemaking Analyses and Notices

I. Executive Summary

NHTSA is issuing this final rule to achieve two goals. First, NHTSA
is establishing FMVSS No. 305a, ``Electric-powered Vehicles: Electric
Powertrain

[[Page 104319]]

Integrity,'' to upgrade and replace existing FMVSS No. 305. The new
FMVSS No. 305a has all the requirements of FMVSS No. 305 and expands
its applicability to vehicles with a gross vehicle weight rating (GVWR)
greater than 4,536 kilograms (kg) (10,000 pounds (lb)). FMVSS No. 305a
also adds requirements and test procedures covering new aspects of
electric vehicle safety, such as performance requirements for the
propulsion battery system, also referred to as the Rechargeable
Electrical Energy Storage System (REESS). NHTSA is also establishing a
new regulation, 49 CFR part 561 (part 561), ``Documentation for
Electric-powered Vehicles,'' to require that manufacturers submit, at
NHTSA's request, documentation addressing safety risk mitigation under
specified scenarios to demonstrate that they considered, assessed, and
mitigated risks for safe operation of the vehicle. Manufacturers are
also required to submit documentation to ensure both first \1\ and
second \2\ responders have access to vehicle-specific information about
extinguishing REESS fires and mitigating safety risks associated with
stranded energy \3\ when responding to emergencies. The restructured
and upgraded FMVSS No. 305a will facilitate future updates to the
standard as battery technologies and charging systems continue to
evolve.
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\1\ ``First responder'' means a person with specialized training
such as a law enforcement officer, paramedic, emergency medical
technician, and/or firefighter, who is typically one of the first to
arrive and provide assistance at the scene of an emergency.
\2\ ``Second responder'' means a worker who supports first
responders by cleaning up a site, towing vehicles, and/or returning
services after an event requiring first responders.
\3\ Stranded energy is the energy remaining inside the REESS
after a crash or other incident.
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The second goal is to further NHTSA's effort to harmonize the
Federal Motor Vehicle Safety Standards under the Economic Commission
for Europe 1998 Global Agreement (``1998 Agreement''). The efforts of
the U.S. and other contracting parties to the 1998 Agreement culminated
in the establishment of Global Technical Regulation (GTR) No. 20,
``Electric Vehicle Safety.'' \4\ FMVSS No. 305 already incorporates a
substantial portion of GTR No. 20's requirements due to a previous
NHTSA rulemaking. In 2017, NHTSA amended FMVSS No. 305 to include
electrical safety requirements from GTR No. 13, ``Hydrogen and fuel
cell vehicles,'' pertaining to electric vehicle performance during
normal vehicle operation and post-crash.\5\ Because GTR No. 13's
provisions for electric vehicles were later incorporated into what
would become GTR No. 20, the 2017 final rule that adopted GTR No. 13's
provisions adopted what later became many of the requirements of GTR
No. 20. That 2017 rulemaking, however, did not expand the applicability
of FMVSS No. 305 to include heavy vehicles nor did it include
requirements for the REESS. This final rule largely adopts these and
other GTR No. 20 requirements.
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\4\ GTR No. 20, <a href="https://unece.org/fileadmin/DAM/trans/main/wp29/wp29wgs/wp29gen/wp29registry/ECE-TRANS-180a20e.pdf">https://unece.org/fileadmin/DAM/trans/main/wp29/wp29wgs/wp29gen/wp29registry/ECE-TRANS-180a20e.pdf</a>.
\5\ GTR No. 13 only applied to light vehicles. Normal vehicle
operations include operating modes and conditions that can
reasonably be encountered during typical operation of the vehicle,
such as driving, parking, standing in traffic with the vehicle in
drive mode, and charging. Final rule, 82 FR 44950, September 27,
2017.
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The notice of proposed rulemaking (NPRM) preceding this final rule
was published on April 15, 2024. The comment period closed on June 14,
2024. After carefully reviewing the comments, NHTSA is adopting the
proposed requirements with some changes from the NPRM. Commenters to
the NPRM commented on the applicability to heavy vehicles; vehicle-
level testing; technical details on documentation requirements; test
procedures for evaluating fire risk mitigation; warning in the case of
a thermal event in the battery pack; and water exposure safety. NHTSA
addresses the comments in this final rule with minor changes to the
regulatory text. These changes include edits to definitions and test
procedures for clarity and accuracy, addition of a provision to exempt
out-of-reach rooftop charging systems from direct contact protection
requirements, and new regulation part 561 for documentation
requirements and emergency response information requirements.

High Level Summary of the Final Rule

FMVSS No. 305 currently only applies to passenger cars and to
multipurpose passenger vehicles, trucks, and buses with a GVWR of 4,536
kg (10,000 lb) or less (``light vehicles''). Consistent with GTR No.
20, FMVSS No. 305a expands the current applicability of FMVSS No. 305
to vehicles with a GVWR greater than 4,536 kg (10,000 lb) (``heavy
vehicles''). Under the final FMVSS No. 305a, light vehicles will be
subject to requirements carried over from FMVSS No. 305 that ensure the
safety of the electrical system during normal vehicle operations and
after a crash (post-crash). They will also be subject to new
requirements for the REESS. Heavy vehicles will be subject to the
requirements for electrical system safety during normal vehicle
operations and to requirements for the REESS. However, except for heavy
school buses, they will not be subject to post-crash requirements.
Heavy school buses (GVWRs greater than 4,536 kg (10,000 lb)) will be
subject to the requirements for electrical system safety during normal
vehicle operations and to the requirements for the REESS, and will have
to meet post-crash test requirements to ensure the vehicles protect
against unreasonable risk of electric shock and risk of fire after a
crash. The post-crash tests are the same tests described in FMVSS No.
301 for heavy school buses (impacted at any point and at any angle by a
moving contoured barrier).
The post-crash requirements of FMVSS No. 305a for light vehicles
and heavy school buses include electric shock protection (there are
four compliance options: low voltage, electrical isolation, protective
barrier, and low energy for capacitors); REESS retention; electrolyte
leakage; and fire safety. The requirements for REESS retention and
electrolyte leakage are already in FMVSS No. 305, but the final rule
adopts the NPRM proposal to enhance some provisions consistent with GTR
No. 20.
FMVSS No. 305a also includes new and comprehensive performance
requirements and risk mitigation strategies for safety of the REESS.
These REESS requirements will apply to all vehicles, regardless of
GVWR. A REESS provides electric energy for propulsion and may include
necessary ancillary systems for physical support, thermal management,
electronic controls, and casings. The requirements set a level of
protection of the REESS against external fault inputs, ensure the REESS
operations are within the manufacturer-specified functional range, and
increase the likelihood of safe operation of the REESS and other
electrical systems of the vehicle during and after water exposure
during normal vehicle operations.
The final rule addresses some aspects of REESS safety through
documentation measures, consistent with GTR No. 20. ``Documentation
measures'' means a list of information provided by manufacturers, at
NHTSA's request, that demonstrates that they considered, assessed, and
mitigated identified risks for safe operation of the vehicle. The final
rule's documentation requirements address: (a) safety risk mitigation
associated with charging and discharging during low temperature; (b)
providing a warning if there is a malfunction of vehicle controls that
manage REESS safe operation; (c)

[[Page 104320]]

providing a warning if there is a thermal event in the REESS; \6\ and
(d) safety risk mitigation for thermal runaway and propagation due to
an internal short circuit of a single cell. The GTR takes a
documentation approach to these aspects of safety because of the
rapidly evolving electric vehicle technologies and the variety of
available REESS and electric vehicle designs. NHTSA agrees that there
are currently no objective test procedures in these specified areas
that are not design restrictive given the current state of knowledge.
Thus, until test procedures and performance criteria can be developed
for all vehicle powertrain architectures, 49 CFR part 561 will require
manufacturers to submit documentation to NHTSA, at NHTSA's request,
that identifies all known safety hazards, describes their risk
mitigation strategies for the safety hazards, and, if applicable,
describes how they provide a warning to address a safety hazard. The
purpose of the documentation approach is two-fold. Given the variation
of battery design and design specific risk mitigation systems, the
documentation requirement will be a means of ensuring that each
manufacturer has identified safety risks and safety risk mitigation
strategies. The requirement provides a means for NHTSA to learn of the
risks associated with the REESS, understand how the manufacturer is
addressing the risks, and oversee those safety hazards. This approach
is battery technology neutral, not design restrictive, and is intended
to evolve over time as battery technologies continue to rapidly evolve.
It is an interim measure intended to ensure that manufacturers will
identify and address the safety risks of the REESS until such time as
objective performance standards can be developed that can be applied to
all applicable REESS designs.
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\6\ The NPRM proposed to include a thermal warning requirement
and a corresponding test procedure. After consideration of comments,
the final rule specifies an additional documentation requirement in
part 561 for the REESS thermal event warning instead of a
corresponding test procedure with the warning requirement.
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As part of NHTSA's battery initiative and in response to a 2020
NTSB recommendation,\7\ the NPRM proposed to include in FMVSS No. 305a
a requirement that vehicle manufacturers submit to NHTSA standardized
emergency response guides (ERGs) and rescue sheets for each vehicle
make, model, and model year. The uploaded ERGs and rescue sheets will
be publicly available on NHTSA's website for easy searchable access.
ERGs and rescue sheets communicate vehicle-specific information related
to fire, submersion, and towing, as well as the location of components
in the vehicle that may expose the vehicle occupants or rescue
personnel to risks, the nature of a specific function or danger, and
devices or measures which inhibit a dangerous state. The final rule
adopts the proposed requirement to submit standardized emergency
response information to a NHTSA website in part 561. The standardized
information will be available and understandable to first and second
responders so they can easily refer to vehicle-specific rescue
information en route to or at the scene of a crash or fire event and
respond to the emergency quickly and safely.
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\7\ ``Safety risks to emergency responders from lithium-ion
battery fires in electric vehicles,'' Safety Report NTSB/SR-20/01,
PB2020-101011, National Transportation Safety Board, <a href="https://www.ntsb.gov/safety/safety-studies/Documents/SR2001.pdf">https://www.ntsb.gov/safety/safety-studies/Documents/SR2001.pdf</a>.
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\8\ 49 U.S.C. 322(a); 49 CFR 1.95.
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NHTSA believes there are no notable costs associated with this
final rule. This final rule closely mirrors the electrical safety
provisions of GTR No. 20, which have been voluntarily implemented by
manufacturers in this country. The agency believes that the finalized
safety standards are widely implemented by manufacturers of light and
heavy electric vehicles and heavy electric school buses. Manufacturers
are also already providing emergency response information to the
National Fire Protection Association (NFPA); under part 561, they would
just have to standardize the format and submit the information to
NHTSA.

II. Background

a. Overview of FMVSS No. 305

The purpose of FMVSS No. 305, ``Electric-powered vehicles:
electrolyte spillage and electrical shock protection,'' is to reduce
deaths and injuries from electrical shock. The standard applies only to
light vehicles (vehicles with a GVWR less than or equal to 4,536 (kg)
(10,000 (lb)). The standard's requirements reduce the risk of harmful
electric shock: (a) during normal vehicle operation; and (b) in post-
crash situations to protect vehicle occupants, and rescue workers and
others who may come in contact with the vehicle after a crash. The
standard's requirements for the former protect against direct and
indirect contact of high voltage sources during everyday operation of
the vehicles. The focus of the ``in-use'' testing (unlike ``post-
crash'' testing) deals with performance criteria that will be assessed
without first exposing the vehicle to a crash test. The standard's
post-crash test requirements address electrical isolation following
frontal, rear, and side impacts of the vehicle, in addition to limiting
electrolyte spillage from propulsion batteries.
FMVSS No. 305 already has many of GTR No. 20's requirements for
light vehicles, including requirements for electrical safety during
normal vehicle operation; post-crash electrolyte spillage; post-crash
REESS retention; and most of the GTR's post-crash electrical safety
options for high voltage sources.

b. Overview of GTR No. 20

1. The GTR Process
The United States is a contracting party to the Agreement
concerning the Establishing of Global Technical Regulations for Wheeled
Vehicles, Equipment and Parts which can be fitted and/or be used on
Wheeled Vehicles (``1998 Agreement''). This agreement entered into
force in 2000 and is administered by the UN Economic Commission for
Europe's (UN ECE's) World Forum for the Harmonization of Vehicle
Regulations (WP.29). The purpose of this agreement is to establish
Global Technical Regulations (GTRs).
In March 2012, UNECE WP.29 formally adopted the proposal to
establish GTR No. 20 at its one-hundred-and-fifty-eighth session. NHTSA
chaired the development of GTR No. 20 and voted in favor of
establishing GTR No. 20.
As a Contracting Party Member to the 1998 Global Agreement that
voted in favor of GTR No. 20, NHTSA is obligated to initiate the
process used in the U.S. to adopt the GTR as an agency regulation. This
process was initiated by the NPRM published on April 15, 2024.

[[Page 104321]]

NHTSA is not obligated to adopt the GTR after initiating this process.
In deciding whether to adopt a GTR as an FMVSS, NHTSA follows the
requirements for NHTSA rulemaking, including the Administrative
Procedure Act, the National Traffic and Motor Vehicle Safety Act
(Vehicle Safety Act), Presidential Executive Orders, and DOT and NHTSA
policies, procedures, and regulations. Among other things, FMVSSs
issued under the Vehicle Safety Act ``shall be practicable, meet the
need for motor vehicle safety, and be stated in objective terms.''
2. GTR No. 20
GTR No. 20 establishes performance-oriented requirements that
reduce potential safety risks of electric vehicles while in use and
after a crash event. The GTR includes provisions that address
electrical shock associated with high voltage circuits of EVs and
potential hazards associated with lithium-ion batteries and/or other
REESS. One of the principles for developing GTR No. 20 was to address
unique safety risks posed by electric vehicles and their components to
ensure a safety level equivalent to conventional vehicles with internal
combustion engines.
The requirements in GTR No. 20, for Phase 1 in the GTR development
process, address issues relating to the safe operation of the REESS,
and the mitigation of fire risk and other safety risks associated with
the REESS. Phase 2 of the GTR No. 20 development process, which is
ongoing, will address issues involving long-term research and
verification.
GTR No. 20 applies to all electric-powered vehicles regardless of
GVWR, in contrast to FMVSS No. 305, which only applies to light
vehicles. FMVSS No. 305 currently includes the majority of GTR No. 20's
requirements regarding electric shock protection and applies these only
to light vehicles. GTR No. 20 also has safety requirements for the
REESS beyond those in FMVSS No. 305. A summary of these additional
requirements in GTR No. 20 for the REESS includes:
Safe operation of REESS under the following exposures during normal
vehicle operations:

<bullet> REESS protection under external fault conditions and extreme
operating temperatures:
[cir] External short circuit
[cir] Overcharge
[cir] Over-discharge
[cir] Overcurrent
[cir] High operating temperature
[cir] Low operating temperature
<bullet> Management of REESS emitted gases
<bullet> Water exposure during vehicle washing and driving through 10-
centimeter (cm) deep water on roadway
<bullet> Thermal shock and cycling (-40 [deg]C to 60 [deg]C)* \9\
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\9\ The asterisk notes that the NPRM did not propose to adopt
the GTR No. 20 requirement.
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<bullet> Resistance to short duration external gasoline pool fire *
<bullet> Vibration environment during normal vehicle operations *

Warning systems for REESS safe operation in case of:

<bullet> Low energy content in REESS *
<bullet> REESS control operational failure
<bullet> Thermal runaway propagation due to single cell short circuit
in REESS
<bullet> Thermal event in REESS
<bullet> Installation (location) of REESS on the vehicle \10\
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\10\ This requirement is intended for countries with type
approval systems where a generic REESS can be approved separately
from the vehicle. A vehicle with a pre-approved REESS that complies
with the REESS installation requirement would not have to undergo
post-crash safety assessment for approval. This installation
requirement would not apply in the U.S. with a self-certification
system.

GTR No. 20 includes post-crash requirements but does not specify
the crash tests for post-crash evaluation. Instead, the GTR allows
contracting parties to apply the crash tests in their regulations.
Further, the GTR allows contracting parties to permit regulated
entities to comply with post-crash requirements without conducting
vehicle crash tests. In place of crash tests, a contracting party may
specify tests for ``mechanical integrity'' and ``mechanical shock'' of
the REESS.
The April 2024 NPRM \11\ proposed to complete the alignment of
FMVSS No. 305 with GTR No. 20 by proposing to establish FMVSS No. 305a,
which adopts all the requirements in FMVSS No. 305 and extends the
standard's electrical safety requirements to heavy vehicles. The NPRM
also proposed to adopt the above requirements under normal vehicle
operations for the REESS to light and heavy vehicles, except as noted
by an asterisk, because requirements for thermal shock and cycling,
resistance to short duration external pool fire, and vibration
environment are already included under United States Hazardous
Materials Regulations (HMR), 49 CFR parts 171 to 180, in accordance
with the international lithium battery transportation requirements of
UN 38.3, ``Transport of dangerous goods: Manual of tests and
criteria.'' The NPRM proposed adding the post-crash test requirements
in FMVSS No. 305 for light vehicles and adding a crash test for all
school buses similar to that in FMVSS No. 301, ``Fuel system
integrity.'' The NPRM also proposed a post-crash requirement for no
observed fire or explosion in the vehicle for a duration of one hour
after the crash test and a low energy post-crash option for capacitors
in the electric power train to meet electrical safety requirements.
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\11\ 89 FR 26704 (Apr. 15, 2024).
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c. Statutory Authority

NHTSA is issuing this final rule pursuant to and in accordance with
its authority under the National Traffic and Motor Vehicle Safety Act
(Safety Act). Under 49 United States Code (U.S.C.) Chapter 301, Motor
Vehicle Safety (49 U.S.C. 30101 et seq.), the Secretary of
Transportation is responsible for prescribing motor vehicle safety
standards that are practicable, meet the need for motor vehicle safety,
and are stated in objective terms (section 30111(a)). ``Motor vehicle
safety'' is defined in the Safety Act (section 30102(a)(8)) as ``the
performance of a motor vehicle or motor vehicle equipment in a way that
protects the public against unreasonable risk of accidents occurring
because of the design, construction, or performance of a motor vehicle,
and against unreasonable risk of death or injury in an accident, and
includes nonoperational safety of a motor vehicle.'' ``Motor vehicle
safety standard'' means a minimum standard for motor vehicle or motor
vehicle equipment performance (section 30102(a)(9)). When prescribing
such standards, the Secretary must consider all relevant available
motor vehicle safety information (section 30111(b)(1)). The Secretary
must also consider whether a proposed standard is reasonable,
practicable, and appropriate for the particular type of motor vehicle
or motor vehicle equipment for which it is prescribed (section
30111(b)(3)) and the extent to which the standard will further the
statutory purpose of reducing traffic accidents and associated deaths
and injuries (section 30111(b)(4)). The responsibility for promulgation
of FMVSSs is delegated to NHTSA (49 CFR 1.95).
The Safety Act also authorizes NHTSA to require manufacturers to
retain certain records and/or make information available to NHTSA.
Section 30166 of the Act provides NHTSA the ability to request and
inspect manufacturer records that are necessary to enforce the
prescribed regulations. NHTSA is also authorized by delegation to issue
regulations to

[[Page 104322]]

carry out the agency's duties of ensuring vehicle safety.\12\
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\12\ 49 U.S.C. 322(a). This provision states that the Secretary
of Transportation may prescribe regulations to carry out the duties
and powers of the Secretary. The authority to implement the Vehicle
Safety Act has been delegated to NHTSA.
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d. Overview of the Final Rule Requirements

Consistent with GTR No. 20, the new FMVSS No. 305a expands the
current applicability of FMVSS No. 305 to vehicles with a GVWR greater
than 4,536 kg (10,000 lb) (``heavy vehicles''). Under FMVSS No. 305a:
<bullet> Light vehicles are subject to requirements carried over
from FMVSS No. 305 that ensure the safety of the electrical system
during normal vehicle operations and after a crash (post-crash).\13\
They are also subject to new requirements for the REESS.
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\13\ Current FMVSS No. 305 light vehicle post-crash test
requirements (front, side, and rear crashes) are aligned with FMVSS
No. 301's light vehicle post-crash test requirements.
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<bullet> Heavy vehicles are subject to the requirements for
electrical system safety during normal vehicle operations and to
requirements for the REESS. However, except for heavy school buses,
they are not subject to post-crash requirements. This exclusion of
heavy vehicles, other than school buses, from crash tests, aligns with
similar exclusions in FMVSS No. 301, ``Fuel system integrity,'' for
conventional fuel vehicles and FMVSS No. 303, ``Fuel system integrity
of compressed natural gas vehicles,'' for compressed natural gas
vehicles.
<bullet> Heavy school buses (GVWRs greater than 4,536 kg (10,000
lb)) \14\ are subject to the requirements for electrical system safety
during normal vehicle operations and to the requirements for the REESS,
and have to meet post-crash test requirements to ensure the vehicles
protect against unreasonable risk of electric shock and risk of fire
after a crash. The post-crash tests are the same tests described in
FMVSS No. 301 for heavy school buses (impacted at any point and at any
angle by a moving contoured barrier).
---------------------------------------------------------------------------

\14\ In the school bus safety area, stakeholders, including
NHTSA, commonly refer to buses with a GVWR over 4,536 kg (10,000 lb)
as ``large'' school buses.
---------------------------------------------------------------------------

The post-crash requirements of FMVSS No. 305a for light vehicles
and heavy school buses include electric shock protection (there are
four compliance options: low voltage, electrical isolation, protective
barrier, and low energy for capacitors); REESS retention; electrolyte
leakage; and fire safety. The requirements for REESS retention and
electrolyte leakage are in FMVSS No. 305, but FMVSS No. 305a enhances
some provisions consistent with GTR No. 20. For example, FMVSS No. 305
does not specify that there must be no fire or explosion after a crash
test. Electric vehicles may catch fire long after a collision or other
occurrence resulting in a fault condition. To account for the potential
delayed response, FMVSS No. 305a is prohibiting fire or explosion for a
one-hour post-test period.
A substantial portion of FMVSS No. 305a focuses on safety
provisions for the propulsion battery, the REESS. FMVSS No. 305a
includes comprehensive performance requirements for the REESS. These
REESS requirements apply to all vehicles, regardless of GVWR. A REESS
provides electric energy for propulsion and may include necessary
ancillary systems for physical support, thermal management, electronic
controls, and casings. The requirements set a level of protection of
the REESS against external fault inputs, ensure the REESS operations
are within the manufacturer-specified functional range, and increase
the likelihood of safe operation of the REESS and other electrical
systems of the vehicle during and after water exposure during normal
vehicle operations.
This final rule addresses some aspects of REESS safety through
documentation measures, consistent with GTR No. 20, through a new
regulation, part 561. ``Documentation measures'' means a list of
information provided by manufacturers, at NHTSA's request, that
demonstrates that they considered, assessed, and mitigated identified
risks for safe operation of the vehicle. These documentation
requirements address: (a) safety risk mitigation associated with
charging and discharging during low temperature; (b) providing a
warning if there is a malfunction of vehicle controls that manage REESS
safe operation; (c) providing a warning if there is a thermal event in
the REESS; and (d) safety risk mitigation for thermal runaway and
propagation due to an internal short circuit of a single cell. The GTR
takes a documentation approach to these aspects of safety because of
the rapidly evolving electric vehicle technologies and the variety of
available REESS and electric vehicle designs. The Informal Working
Group experts that drafted the GTR determined there currently are no
objective test procedures to evaluate safety risk mitigation designs or
the operations of warnings of a malfunction of vehicle controls in a
manner that is not design restrictive.
NHTSA agrees with this approach given the current state of
knowledge. Thus, until test procedures and performance criteria can be
developed for all vehicle powertrain architectures, manufacturers will
be required to submit documentation to NHTSA, at NHTSA's request, that
identifies all known safety hazards, describes risk mitigation
strategies for the safety hazards, and, if applicable, describes how
they provide a warning to address a safety hazard.\15\ The purpose of
the documentation approach is two-fold. Given the variation of battery
design and design specific risk mitigation systems, the documentation
requirement is a means of ensuring that each manufacturer has
identified safety risks and safety risk mitigation strategies. The
requirement provides a means for NHTSA to learn of the risks associated
with the REESS, understand how the manufacturer is addressing the
risks, and oversee those safety hazards. This approach is battery
technology neutral, not design restrictive, and is intended to evolve
over time as battery technologies continue to rapidly evolve. It is an
interim measure intended to ensure that manufacturers will identify and
address the safety risks of the REESS until such time as objective
performance standards can be developed that can be applied to all
applicable REESS designs. NHTSA will also acquire information from the
submissions to learn about the safety of the REESSs and potentially
develop the future performance standards for FMVSS No. 305a. The
documentation requirements are based on the approach of GTR No. 20, but
NHTSA focused the GTR's documentation requirements to enable the agency
to obtain more targeted information from manufacturers.
---------------------------------------------------------------------------

\15\ Section 30166 of the Vehicle Safety Act authorizes the
Secretary of Transportation (NHTSA by delegation) the ability to
request and inspect manufacturer records that are necessary to
enforce the prescribed regulations.
---------------------------------------------------------------------------

As part of NHTSA's battery initiative,\16\ this final rule also
establishes, through regulation, a requirement that vehicle
manufacturers submit to NHTSA emergency response guides (ERGs) and
rescue sheets for each vehicle make, model, and model year. The purpose
of the requirement is to provide information to first and second
responders regarding the safe handling of the vehicle in emergencies
and for towing and storing operations. The uploaded ERGs and rescue
sheets will be publicly available on NHTSA's website for easy
searchable access. ERGs and rescue sheets communicate vehicle-specific
information related to fire, submersion, and towing, as well as the

[[Page 104323]]

location of components in the vehicle that may expose the vehicle
occupants or rescue personnel to risks, the nature of a specific
function or danger, and devices or measures which inhibit a dangerous
state.
---------------------------------------------------------------------------

\16\ <a href="https://www.nhtsa.gov/battery-safety-initiative">https://www.nhtsa.gov/battery-safety-initiative</a>.
---------------------------------------------------------------------------

NHTSA is requiring standardized formatting of the information. The
ERG and rescue sheet requirements include the layout and format
specified in ISO-17840, ``Road vehicles--Information for first and
second responders,'' which standardize color-coded sections in a
specific order to help first and second responders quickly identify
pertinent vehicle-specific rescue information. The standardized
information will be available and understandable to first and second
responders so they can easily refer to vehicle-specific rescue
information enroute to, or at the scene of, a crash or fire event and
respond to the emergency quickly and safely.

e. Changes From the NPRM to the Final Rule

In developing this final rule, NHTSA made some modifications to the
proposed regulatory requirements in response to comments received and
to improve clarity and accuracy of the regulatory text. In addition to
typographical corrections, the final rule differs from the April 2024
NPRM in the following ways:
1. Timing of voltage measurements for determining electrical
isolation post-crash. The proposal required voltage measurements for
assessment of post-crash electrical isolation to be made between 10 to
60 seconds from the time of impact. The final rule requires the voltage
measurements for post-crash electrical isolation assessment to be made
at least 10 seconds after impact. NHTSA determined that taking all the
voltage measurements for determining electrical isolation would
typically take more than 60 seconds and since electrical isolation
value is not expected to change with time, only specifying a minimum
time after impact for making the measurements is sufficient.
2. Definition of State of Charge (SOC). The definition of SOC was
updated to clarify that it is the available electric charge in a REESS
expressed as a percentage of its normal operating capacity specified by
the manufacturer and not as a percentage of the total charge (stored
energy) in the REESS.
3. Documentation requirements included in part 561. The NPRM
proposed documentation requirements in FMVSS No. 305a for manufacturers
to submit, upon request, documentation regarding vehicle and REESS
designs to mitigate the risk of vehicle fire and explosion resulting
from single cell thermal runaway in the REESS, loss or malfunction of
controls managing safe operation of the REESS, and vehicle operations
at low temperatures. The NPRM also proposed requiring manufacturers to
submit emergency response information to a repository prior to the
certification time of the vehicle. The final rule has moved these
requirements to part 561 because documentation requirements without
corresponding test procedures are better suited in a regulation.
Additionally, the final rule requires emergency response information to
be submitted to NHTSA's repository before first sale or lease of the
vehicle model upon the compliance date.
4. Thermal event warning documentation requirement. The NPRM
proposed a test procedure to evaluate the warning function resulting
from a thermal event in the REESS. Due to practicability and safety
concerns with the proposed test procedure, the final rule specifies an
additional documentation requirement in part 561 for the REESS thermal
event warning instead of a corresponding test procedure with the
warning requirement.
5. Maximum time to conduct driving through standing water test
(protection against water exposure). The NPRM proposed a maximum test
duration of 5 minutes for the driving through standing water test.
Based on NHTSA's recent testing, the final rule extends this time to 10
minutes because of the practicability concerns for conducting the test
within 5 minutes for water pools shorter than 500 meters.
7. Exclusion for rooftop charging systems. The final rule excludes
those high voltage devices on heavy vehicles not energized except
during charging of the REESS, that are installed out of reach on the
vehicle rooftop, from direct contact protection requirements. NHTSA
inadvertently excluded this carveout for the out of reach high voltage
devices from the proposed direct contact protection requirements.
8. Addition of loading specifications. The proposed crash test
procedure for heavy school buses inadvertently omitted the loading
specifications. Loading specifications matching FMVSS Nos. 301 and 303
have been added to the final regulatory text for completeness.
9. Compliance dates. The final rule adopts the proposed 1-year lead
time from the date of publication of the final rule to comply with the
emergency response information requirements. The proposed 2-year lead
time for complying with all other requirements for light vehicles is
largely adopted with a slight date change to align with the beginning
of the model year on or after the first September 1 that is at least
two years after the publication of the final rule. In response to
comments received, the final rule extends the heavy vehicles' lead time
to comply with the requirements other than the emergency response
information requirements to the first September 1 that is at least
three years after the publication of the final rule.

III. Summary of Comments

The NPRM preceding this final rule included requests for comment on
several topics, including the post-crash requirements, the thermal
event warning performance test, the water exposure tests, the exclusion
of some GTR No. 20 requirements, and the documentation requirements.
From April 15, 2024, to June 14, 2024, the agency received 38 comments
on the NPRM, including one that appears to be an accidental duplicate
submission. The comments were generally supportive of the proposed
rule, particularly with regard to the collection of standardized
emergency response information and harmonization with international
regulations. Many commenters suggested modifications to the proposed
requirements, including establishing documentation requirements in a
separate regulation instead of the FMVSS. Of the 37 unique comments,
the majority (26 comments) were submitted by vehicle and component
manufacturers and industry associations. Comments were also submitted
by standards testing laboratories (3 comments), a government agency (1
comment), and other stakeholders (7 comments).
The vehicle and component manufacturers that provided comments were
American Honda Motor Co. (``Honda''), Blue Bird Body Company (``Blue
Bird''), Bugatti Rimac d.o.o. (``Bugatti''), Daimler Truck North
America (``DTNA''), Eaton Corporation (``Eaton''), Ford Motor Company
(``Ford''), Freudenberg Battery Power Systems (``Freudenberg''),
Honeywell International (``Honeywell''), Hyundai America Technical
Center (``HATCI'' or ``Hyundai''), Lubrizol Corporation (``Lubrizol''),
Lucid Motors (``Lucid''), Navistar, New Flyer of America (``NFA''),
Nikola Corporation (``Nikola''), Nissan North America (``Nissan''),
Prevost, Rivian Automotive (``Rivian''), Tesla, and Volkswagen Group of
America (``Volkswagen'').
The industry associations that provided comments were the Alliance
for Automotive Innovation (``Auto Innovators''), Coalition for Safe

[[Page 104324]]

Autonomous Vehicles and Electrification (``SAVE Coalition''), Electric
Drive Transportation Association (``EDTA''), MEMA Vehicle Suppliers
Association (``MEMA''), National Electrical Manufacturers Association
(``NEMA''), Truck and Engine Manufacturers Association (``EMA''), and
Zero Emission Transportation Association (``ZETA''). Some manufacturers
that submitted comments individually indicated that they belong to one
of these industry associations and/or stated support for the comments
submitted by an industry association.
The standards testing laboratories and associations that provided
comments were UL Solutions, the American Council of Independent
Laboratories (``ACIL''), and the American Association for Laboratory
Accreditation (``A2LA'').
The National Transportation Safety Board (``NTSB'') submitted one
comment, expressing strong support for the proposed rulemaking.
The other stakeholders that provided comments were the Center for
Auto Safety (``CAS''), Consumer Reports, Creaform/Ametek
(``Creaform''), Electric Vehicle Rescue App (``EV Rescue App,'' two
comments), Michael Lillo, and Kurt Vollmacher.
With regard to heavy vehicles, the commenters generally expressed
support for the proposed requirements for heavy school buses. Comments
on applying additional requirements to other heavy vehicles were more
varied, with some commenters in favor of additional test requirements
at the component level or at the vehicle level, and others opposed. One
commenter requested that NHTSA add an exemption from the direct contact
protection requirements during normal vehicle operation for rooftop
charging systems on heavy vehicles.
With regard to post-crash safety, manufacturers expressed support
for the inclusion of the low energy option for capacitors. Commenters
also generally agreed with the proposed requirement that there be no
evidence of fire or explosion for the duration of one hour after each
crash test. Comments on the voltage measurement procedure were mixed,
with some commenters in agreement and others requesting changes to the
test specifications. Honda and Auto Innovators requested removal of the
60-second time limit for post-crash electrical isolation measurements,
which would align the specification with GTR No. 20. For electrolyte
leakage, commenters said that the updated terminology is appropriate,
but the 5-liter maximum leakage requirement is no longer relevant with
modern REESS chemistries.
With regard to the proposed requirements for safe operation of the
REESS, commenters commented about certain aspects of the proposed test
procedures, particularly the state of charge, breakout harness
location, and test termination specifications. Many comments from
industry disagreed with the agency's exclusion of component-level
compliance test options. For the thermal event warning, some commenters
also requested implementation of a documentation requirement instead of
a test requirement.
For the proposed documentation requirements, some commenters
requested clarification of the requirements and implementation in a
separate regulation. Most commenters expressed strong support for
NHTSA's proposed collection of standardized emergency response
information, with a few vehicle manufacturers requesting a modification
to the submission timeline. Some also requested extending the
compliance date for the other proposed requirements beyond 2 years
after publication of the final rule.

IV. Response to Comments on Proposed Requirements

a. Expanding Applicability of FMVSS No. 305a to Heavy Vehicles

1. Normal Vehicle Operations and Requirements for the REESS
Proposed Requirements
Consistent with GTR No. 20, the NPRM proposed to expand the current
applicability of FMVSS No. 305 to heavy vehicles. Under FMVSS No. 305a,
heavy vehicles (including heavy school buses) would have to meet the
same requirements as light vehicles for electrical system safety during
normal vehicle operations and for the REESS. The fundamentals for
protecting against an electrical shock are the same for light vehicles
and heavy vehicles. A failure of a high voltage system may cause
injurious electric shock to the human body.
Comments Received
Commenters generally expressed support for applying the expanded
electrical system safety requirements during normal vehicle operations
to heavy school buses. Comments on applying these requirements to other
heavy vehicles were more varied, with some commenters in favor of
additional test requirements at the component level or at the vehicle
level, and others opposed. MEMA agreed with the inclusion of heavy-duty
vehicles without crash testing. Auto Innovators commented that FMVSS
No. 305a should not apply to heavy vehicles at this time and more
research is needed. Auto Innovators noted that the proposed regulatory
requirements that were not previously applicable to heavy vehicles have
potential design implications that require thorough consideration by
the agency.
EMA disagreed specifically with application of the REESS
overcurrent test to heavy vehicles, which were exempted in GTR No. 20.
EMA said that NHTSA did not provide justification for applying the
overcurrent test requirement to heavy vehicles. EMA also requested that
NHTSA include an exemption from GTR No. 20 related to direct contact
protection during normal vehicle operation. Specifically, EMA stated
that the proposed requirement omitted an important exemption provision
for some heavy vehicle applications. Under this provision, conductive
connection devices not energized except during charging of the REESS
that are located on the roof of the vehicle and out of reach of a
person standing outside the vehicle are exempted from direct contact
protection requirements. EMA explained that this exemption is necessary
for rooftop pantograph charging systems used in some heavy vehicles
like transit buses.
Agency Response
The agency is adopting most of the requirements for heavy vehicles
as proposed in the NPRM, with one modification. Unlike the NPRM, the
final rule excludes direct contact protection requirements from those
high voltage devices on heavy vehicles not energized except during
charging of the REESS, that are installed out of reach on the vehicle
rooftop. NHTSA inadvertently excluded this carveout for high voltage
rooftop charging devices on heavy vehicles from the direct contact
protection provision in the proposed requirements for FMVSS No. 305a.
GTR No. 20 excludes high voltage sources that are not energized except
during charging of the REESS from direct contact protection
requirements if they are located on the vehicle rooftop such that the
wraparound distance from the instep of the vehicle, or the lowest step
(if multiple steps are present) of the vehicle, to the high voltage
source is at least 3 meters. NHTSA agrees that if the high voltage live
parts are not energized except during charging of the REESS and are out
of reach for a person standing outside of the vehicle, it is
appropriate to exempt those parts from the IPXXB direct contact
protection

[[Page 104325]]

requirement. NHTSA has included the relevant language in the regulatory
text of the final rule.
EMA also requested not applying the overcurrent test to heavy
vehicles. The overcurrent test in GTR No. 20 is applicable to light
vehicles that have the capability to be charged by an external DC
supply. GTR No. 20 states that the overcurrent test for heavy vehicles
will be considered in Phase 2, ``as it is unclear how to apply on
vehicles that have different charging technologies.'' GTR No. 20
specifies two methods of conducting the overcurrent test. In the first
method, the overcurrent is applied through the external DC supply
equipment connected to the vehicle inlet while the vehicle is charging
normally. In the second method, the charge current and the overcurrent
are applied through a breakout harness connected just outside the
REESS. The external DC supply equipment connected to the other end of
the breakout harness supplies the normal charge as well as the
overcurrent to the REESS. The overcurrent test procedure in FMVSS No.
305a uses the breakout harness method, so any challenges associated
with testing via the charging inlet for different charging technologies
are avoided. NHTSA evaluated the overcurrent test using the breakout
harness and found it to be an easy test to conduct that is practical
and feasible for different vehicle types.\17\
---------------------------------------------------------------------------

\17\ Electric Vehicle GTR No. 20 Test Development, Validation,
and Assessment, DOT HS 812 092, April 2021, <a href="https://rosap.ntl.bts.gov/view/dot/55584">https://rosap.ntl.bts.gov/view/dot/55584</a>.
---------------------------------------------------------------------------

Auto Innovators recommended excluding heavy vehicles from FMVSS No.
305a electrical system safety during normal vehicle operations and
REESS requirements at this time, citing the need for more research on
the implications of these requirements on heavy vehicle designs. Auto
Innovators did not provide additional information to support its
statement. NHTSA believes the requirements for normal vehicle
operations and the REESS in FMVSS No. 305a are basic safety measures
that should be included in all electric vehicle designs.\18\ These
basic safety measures ensure protection from electric shock and fire
originating in the electric powertrain and specifically in the REESS.
These measures include electrical isolation, direct and indirect
contact protection, protection of the REESS from abuse and external
inputs that could damage the REESS over time, and measures to ensure
the REESS always operates within its safe operating boundaries. The
agency believes that the requirements proposed in the NPRM for heavy
vehicles, including the overcurrent test requirement, are relevant and
appropriate for heavy vehicle safety and that the test procedures are
practicable.
---------------------------------------------------------------------------

\18\ Lithium-ion Battery Safety Issues for Electric and Plug-in
Hybrid Vehicles, DOT HS 812 418, October 2017, <a href="https://www.nhtsa.gov/sites/nhtsa.gov/files/documents/12848-lithiumionsafetyhybrids_101217-v3-tag.pdf">https://www.nhtsa.gov/sites/nhtsa.gov/files/documents/12848-lithiumionsafetyhybrids_101217-v3-tag.pdf</a>.
---------------------------------------------------------------------------

2. Post-Crash Safety for Heavy School Buses
Proposed Requirements
In addition to the requirements for electrical system safety during
normal vehicle operations and for the REESS, the NPRM also proposed
requirements for post-crash safety of heavy electric school buses. The
NPRM proposed use of a moving contoured barrier test, where a barrier
traveling at any speed up to 48 km/h (30 mph) impacts the school bus at
any point and angle. The crash test requirement aligns FMVSS No. 305a
with the requirements for heavy school buses in FMVSS No. 301, ``Fuel
system integrity,'' and FMVSS No. 303, ``Fuel system integrity of
compressed natural gas vehicles.'' The agency did not propose a
provision in GTR No. 20 that allows the use of component-level
mechanical integrity and mechanical shock tests instead of vehicle
crash tests. NHTSA believes that post-crash safety is better evaluated
at the system level in a crash test.
Comments Received
Commenters were generally in favor of the proposed crash test
requirements for heavy school buses. Commenters NTSB, DTNA, Navistar,
and EV Rescue App expressed full support for the expanded requirements
for heavy school buses. In particular, NTSB agreed with expanding the
post-crash requirements and making full use of the system-level
requirements that exist for heavy school buses so the vehicles will be
subject to the full intent and scope of FMVSS No. 305a. Bus
manufacturers DTNA (Thomas Built Buses) and Navistar (IC Bus) also
agreed with the proposed crash test performance requirements, which are
consistent with FMVSS No. 301 and FMVSS No. 303. Navistar stated that
the proposed requirements for heavy school buses were reasonable and
would not add significant cost or weight to the vehicles. EMA noted
that the loading requirements should be added to the crash test
specifications in S10.2.3. Individual commenter Mr. Lillo also stated
general support for enhanced EV school bus safety and suggested
conducting time trials for bus evacuation.
One manufacturer disagreed with the proposed requirements for heavy
school buses. Blue Bird stated that including multiple post-crash
requirements makes FMVSS No. 305a more burdensome than the
corresponding requirements for non-electric school buses. Blue Bird
also said that the proposed rule would require manufacturers to crash a
school bus every time they make a change to the battery pack. Blue Bird
requested component-level testing instead of full-vehicle testing.
Agency Response
After reviewing the comments, NHTSA is adopting the crash test and
post-crash requirements for heavy school buses as proposed in the NPRM,
with the addition of loading specifications. EMA noted that the
proposed regulatory text in the NPRM did not state the school bus
loading condition for the crash test. This final rule corrects this
inadvertent omission; loading specifications matching FMVSS Nos. 301
and 303, as suggested by EMA, have been added to the regulatory text
for completeness. With regard to potential fire emergencies, in
addition to the requirements of this final rule, electric school buses
are subject to FMVSS No. 217, ``Bus emergency exits and window
retention and release,'' which specifies operating forces, opening
dimensions, and markings for emergency exits on school buses to
facilitate rapid evacuation, and FMVSS No. 302, ``Flammability of
interior materials,'' which specifies burn resistance requirements.
NHTSA will also continue to evaluate school bus safety, including
school bus evacuation, and update applicable safety standards as
technology changes over time.
Most commenters, including bus manufacturers, agreed with the
proposed requirements. The dissenting commenter expressed concerns over
the testing burden. With regard to the crash test requirements for
electric school buses, the dynamic moving contoured barrier test aligns
FMVSS No. 305a with FMVSS Nos. 301 and 303, which address post-crash
safety of heavy school buses using conventional fuel or compressed
natural gas. The four post-crash requirements for FMVSS No. 305a are
electric shock protection, REESS retention, electrolyte leakage, and
fire safety. These requirements do not necessitate multiple crash tests
and can be verified simultaneously. In other words, although there are
four post-crash requirements, only one crash test is needed. There are
also four compliance options for the electric shock protection
requirement to provide flexibility. With regard to repeated full-

[[Page 104326]]

vehicle crash testing for component modifications, the FMVSS specifies
the procedures that NHTSA uses to evaluate compliance. Manufacturers
may use other reasonable methods to certify the compliance of their
vehicles, such as simulations and component-level testing, which they
may find appropriate when making minor changes. The vehicles must meet
the FMVSS when tested by NHTSA according to the test procedures in the
standard. For these reasons, the agency is not persuaded by Blue Bird's
comments on the test burden of conducting full-vehicle crash tests for
school buses. NHTSA maintains that the requirements are reasonable and
appropriate for school bus safety and is adopting all proposed
requirements for heavy school buses from the NPRM.
3. Post-Crash Safety for Other Heavy Vehicles
Proposed Requirements
The NPRM did not propose crash testing requirements for heavy
vehicles other than heavy school buses because there is currently no
available test that would be appropriate for these vehicles. The NPRM
sought comment on applying a moving contoured barrier crash test to all
heavy electric vehicles while acknowledging the cost and practicability
constraints. The NPRM also sought comment on component-level tests that
are representative of actual impact loads in heavy vehicle crashes and
that can be applied to different weight classes of heavy vehicles.
GTR No. 20 provides an option for evaluating post-crash safety of
light vehicles using a mechanical integrity test (crush test) of the
REESS, with a quasi-static load up to 100 kN. GTR No. 20 also includes
a mechanical shock test that evaluates the REESS mountings and fixtures
by accelerating and decelerating the REESS installed on a sled system.
However, as noted in the NPRM, the loads and accelerations specified in
GTR No. 20 may be too low for heavy vehicles. In the absence of
additional data to develop appropriate requirements, the NPRM did not
propose component-level crash testing of heavy vehicle REESS.
Comments Received
Comments on the potential post-crash requirements for heavy
vehicles other than school buses were varied, with some commenters
suggesting vehicle-level or component-level tests and others stating
additional research is needed. NTSB commented that NHTSA should have
proposed the REESS mechanical integrity and mechanical shock test
requirements from GTR No. 20 for heavy vehicles, calling the exclusion
``unnecessary.'' NTSB noted that the component-level tests constitute
an established and applicable standard for heavy vehicle REESS that is
not design-restrictive. Alternatively, NTSB stated, FMVSS No. 305a
could at least include documentation requirements for post-crash safety
of the heavy vehicle REESS. MEMA and Eaton also stated support for the
inclusion of mechanical integrity and mechanical shock tests with
additional isolation criteria.
Heavy vehicle manufacturers, DTNA and Prevost, commented that
additional research should be conducted before establishing test
requirements for post-crash safety of heavy vehicle REESS. DTNA stated
support for the concept of the mechanical integrity test in general,
but said that further research is necessary to develop a repeatable,
reproducible, and practical test method. Prevost said additional
research is needed for mechanical shock testing because accelerations
on the REESS are highly design dependent. While Auto Innovators
disagreed with application of additional requirements to heavy vehicles
in general, Auto Innovators said it did not have significant concerns
about applying the mechanical shock test from GTR No. 20 to heavy
vehicles and suggested refining the test procedure by defining the
acceleration as a function of vehicle mass to provide a more granular
method.
Heavy vehicle manufacturer NFA agreed with NHTSA's assessment that
component-level tests are more appropriate than full scale crash tests
for heavy vehicles due to practicability, as did Navistar and EMA. None
of them provided data on crash loads for heavy vehicles; NFA expressly
stated that it does not have sufficient data to determine test
parameters at this time. NFA pointed to existing standards for
mechanical shock testing, stating that it currently uses the mechanical
shock requirements of UNECE R100, and noting industry standards for
compressed natural gas (CNG) vehicles require that the CNG storage
system can endure an inertial load of 8G, which is within the range of
the component test procedure from GTR No. 20.
Truck manufacturer Nikola stated that it designed and tested its
vehicles based on the moving barrier tests currently in FMVSS Nos. 208,
214, and 305, and recommended that NHTSA likewise use the moving
barrier for any heavy vehicle crash test requirements because it is
more representative of a passenger vehicle. For mechanical shock
testing, Nikola said that test facilities are not currently equipped
with a test apparatus capable of testing Nikola's entire REESS or
subset. Regarding mechanical integrity testing, Nikola disagreed with
establishing a requirement, as it is not required by GTR No. 20 and
Nikola already requires its battery pack manufacturers to follow the UL
2580 standard, which includes a crush test.
Tesla commented that component-level testing is inadequate for
mechanical integrity and mechanical shock testing, stating that the
test will not be representative of the full vehicle, especially if the
battery system must be removed from the vehicle for testing. Creaform,
a 3D measurement and analysis company, also recommended vehicle-level
post-crash requirements for heavy vehicles, saying that vehicle crashes
can impose higher loads on an unprotected REESS than quasi-static crush
tests, depending on the location of the REESS in the vehicle, and that
adjusting the component-level mechanical integrity and mechanical shock
test parameters would not cover the risks. Creaform said advanced
numerical simulations can serve as a lower-cost alternative to vehicle
crash testing. Battery manufacturer Freudenberg also disagreed with
component-level mechanical integrity testing, stating it will place
undue expectations on the battery enclosure. Freudenberg requested
alignment of FMVSS No. 305a with the UNECE regulation, which exempts
heavy vehicles from mechanical integrity test requirements.
Agency Response
In the absence of new data, the agency is not adopting post-crash
requirements for heavy vehicles other than heavy school buses in FMVSS
No. 305a. The agency did not propose post-crash requirements for heavy
vehicles other than school buses in the NPRM because additional
information is needed to develop requirements that are reasonable,
practicable, and appropriate for the vehicles. While NTSB stated that
the component-level tests in GTR No. 20 are appropriate, the comment
did not provide additional information. NTSB also suggested a
documentation requirement for post-crash safety, which was not
discussed in the NPRM and is therefore out of scope for this final
rule.
Comments from heavy vehicle manufacturers indicated that they
currently use industry standards such as UL 2580, ``Electric vehicle
battery testing and certification,'' and other safety regulations in
designing their vehicles and procuring battery packs. The industry
standards used by manufacturers are convenient tools to

[[Page 104327]]

establish best practices in design and generally lack the objectivity
needed for FMVSS. Further research will be needed to evaluate and
modify such testing standards for inclusion in the FMVSS. Further
investigation into heavy vehicle impacts and component-level test
specifications would also address commenters' concerns regarding
accurate representation of crash forces. As none of the comments
provided supporting data, the agency maintains that additional research
is necessary to determine appropriate post-crash requirements and
acceptability criteria for heavy vehicles other than heavy school buses
for future consideration of FMVSS adoption.

b. General Specifications Relating to Crash Testing

The NPRM proposed several general provisions from GTR No. 20 that
would apply to various testing and performance requirements. These
provisions pertain to light vehicles and heavy school buses subject to
the crash testing requirements of the proposed FMVSS No. 305a.
1. Low Energy Option for Capacitors
Proposed Requirements
Currently, FMVSS No. 305 S5.3 requires that vehicles meet one of
the following three criteria post-crash: electrical isolation; absence
of high voltage; or physical barrier protection. The NPRM proposed to
include a post-crash low energy option for capacitors in the electric
powertrain that is included in GTR No. 20. Capacitors store electrical
energy and may be connected directly to the chassis in some electric
power trains. In fuel cell electric vehicles (FCEVs), the high-voltage
systems may contain capacitors that are connected to high voltage buses
and are not electrically isolated. Such capacitors may be high voltage
sources post-crash (because a charged capacitor may not discharge
quickly) and may not be able to comply with post-crash electrical
safety requirements using the direct and indirect contact protection
option or the electrical isolation option. However, capacitors may not
pose a safety hazard when contacted, even though they may be high
voltage sources post-crash, because they are low energy high voltage
sources. NHTSA conducted an analysis of the potential hazard and
concluded that the post-crash electrical safety compliance option for
capacitors based on an electrical energy of 0.2 Joules or less provides
adequate safety from electrical shock and long-term harmful effects on
the human body.
Comments Received
Comments on the low energy option for capacitors were positive,
with manufacturers expressing support for the inclusion. Tesla agreed
that there is no need to fully discharge all the capacitors, and Auto
Innovators noted that the option is consistent with GTR No. 20 and
other applicable international regulations. Auto Innovators suggested
changing the y-capacitor calculation to match ECE 100.03,\19\ noting
that the proposed calculation ``is inconsistent with ECE practice where
the energy of a Y capacitor is the greater of 0.5Cy x
V11[supcaret]2 or 0.5Cy x V2[supcaret]2.'' Auto
Innovators also suggested a minor edit to the text of S8.2 to clarify
that the inclusion of the low energy specification for capacitors is an
additional option for the post-crash electrical safety requirement.
---------------------------------------------------------------------------

\19\ ECE R.100, ``Uniform provisions concerning the approval of
vehicles with regard to specific requirements for the electric power
train,'' <a href="https://unece.org/sites/default/files/2024-01/R0100r3e.pdf">https://unece.org/sites/default/files/2024-01/R0100r3e.pdf</a>.
---------------------------------------------------------------------------

MEMA and Eaton commented that the low energy option for capacitors
in the powertrain should include additional isolation requirements.
MEMA said, ``criteria should include an isolation requirement from all
parts of battery system to the external power output connectors of the
battery pack as is currently included in FMVSS 305 S5.3, as well as
avoiding a single point of failure as a standard and best-practice.''
Eaton recommended the same criteria. MEMA and Eaton referred to these
two additional requirements as ``acceptability criteria,'' and
requested their inclusion in multiple sections.
Agency Response
In response to the comments, the final rule follows the proposal in
including a low energy option for capacitors for post-crash electrical
safety. However, as detailed below, the final rule adopts the GTR No.
20 method of calculating energy in y-capacitors. In addition, the first
paragraph of S8.2 has been edited for clarity and the typographical
errors in S8.2(a)(2) have been corrected as suggested by commenters.
Auto Innovators requested changing the y-capacitor energy
calculation to that in ECE R.100.03. We note that ECE R.100.03 does not
have the post-crash low energy optional method of meeting electric
safety requirements because ECE R.100.03 does not address post-crash
safety. The post-crash low energy option is available in ECE R.94,\20\
and the method of calculating capacitor energy post-crash is similar to
that in GTR No. 20. The NPRM proposed calculating the energy stored in
the two y-capacitors at once, assuming that each capacitance is the
same, and requiring that the total energy not exceed 0.2 Joules.
However, GTR No. 20 calculates the energy in each y-capacitor
separately, using the individual capacitance, and requires that the
energy in each capacitor does not exceed 0.2 Joules. Because the GTR
No. 20 method uses the actual capacitance of each y-capacitor in the
corresponding calculation, and therefore more accurately represents the
stored energy in each, NHTSA is adopting the method from GTR No. 20 and
requiring that the energy in each capacitor not exceed 0.2 Joules.
---------------------------------------------------------------------------

\20\ ECE R.94 Revision 4, ``Concerning the Adoption of
Harmonized Technical United Nations Regulations for Wheeled
Vehicles, Equipment and Parts which can be Fitted and/or be Used on
Wheeled Vehicles and the Conditions for Reciprocal Recognition of
Approvals Granted on the Basis of these United Nations
Regulations,'' <a href="https://unece.org/sites/default/files/2024-07/R094r4e.pdf">https://unece.org/sites/default/files/2024-07/R094r4e.pdf</a>.
---------------------------------------------------------------------------

FMVSS No. 305a includes provisions for electrical isolation. As
proposed, the post-crash electrical safety requirements in FMVSS No.
305a are the same as the current requirements in FMVSS No. 305, except
for the addition of a low energy option for capacitors to comply with
electrical safety requirements. All high voltage sources, including the
REESS, need to be either electrically isolated, contactors open
resulting in low voltage, or have direct and indirect contact
protection. The low energy option for capacitors does not circumvent
the requirements for electrical protection, but rather allows for
another verification method.
The requirement to ensure no single point of failure (e.g., contact
failure) was not discussed in the NPRM and is not in scope of this
rulemaking. The FMVSS requirements are written in a manner to not be
design restrictive, and therefore do not prescribe a particular
connection to the battery due to the variation of battery designs.
However, the requirements for the REESS that are included in FMVSS No.
305a for normal vehicle operations and post-crash scenarios verify that
the system design provides a requisite level of safety. Comprehensive
risk mitigation of potential hazards is further addressed by the
documentation requirements. As discussed later in Section IV.n.,
``Documentation Requirements,'' manufacturers are required to
demonstrate that they have considered and addressed identified safety
risks for their vehicles. Designing separate connections to the battery
and avoiding a single point of failure are examples of risk mitigation
strategies that could be implemented by manufacturers along

[[Page 104328]]

with other protective measures. Additional requirements for the post-
crash low energy option for capacitors, beyond those test and
documentation requirements discussed above, were not included in the
NPRM and so are not in scope for this final rule. NHTSA will continue
to study and discuss further requirements for battery safety, including
additional requirements for post-crash low energy option for
capacitors, during the ongoing efforts on Phase 2 updates to GTR No.
20. Harmonization with the GTR No. 20 Phase 2 updates would be
considered in future updates to the FMVSS No. 305a requirements.
2. Assessing Fire or Explosion in Vehicle Post-Crash Test
Proposed Requirements
In accordance with GTR No. 20, NHTSA proposed to include in FMVSS
No. 305a a requirement that there be no evidence of fire or explosion
for the duration of one hour after the crash test for heavy school
buses, and for the duration of one hour after each crash test and
subsequent quasi-static rollover test for light vehicles. The
assessment of fire or explosion would be verified by inspection without
removal of the REESS or any parts of the vehicle.
Comments Received
Commenters generally agreed with the proposed requirement. MEMA,
Auto Innovators, Lucid, and Nikola stated support, with Nikola saying
that the provision should also apply to heavy vehicles if a crash test
requirement is added. Tesla agreed with the proposal as well but
requested additional guidance and an explicit evaluation procedure. In
contrast to other industry members, SAVE Coalition disagreed with
implementing the requirement at the vehicle level because FMVSS Nos.
208, 214, 301, and 303 do not include the same requirement for other
types of vehicles. SAVE Coalition said, ``If NHTSA's intent is to
regulate fire risks from all vehicle systems, that requirement should
be applied more generally in a regulation covering all vehicles
regardless of powertrain. For the purposes of assessing electric
vehicle safety, and to align with GTR 20 and the stated intent in the
preamble, this requirement should be clarified to be specific to REESS
related fires.''
Agency Response
After considering the comments, NHTSA has decided to adopt the
proposed post-crash requirement that there be no evidence of fire or
explosion. For electric vehicles, thermal runaway and propagation poses
a significant fire risk regardless of electrolyte leakage from the
battery pack, so FMVSS No. 305a addresses fire safety assessment
directly. The post-crash assessment does not require disassembly of the
vehicle or components. Evidence of fire or explosion could include
flames, smoke, scorch marks, or other indications. If such evidence
were visible at any time within the one-hour inspection period
following the crash test, the vehicle would fail to meet the safety
requirement. The agency maintains that the requirement is appropriate
as written.
Regarding SAVE Coalition's concern that only electric vehicles, not
other vehicle types, are subject to post-crash fire assessment, NHTSA
would like to explain the FMVSS safety requirements that were cited.
FMVSS No. 208, ``Occupant crash protection,'' and FMVSS No. 214, ``Side
impact protection,'' apply to vehicles regardless of fuel type and
address the physical forces and accelerations in a crash; electric and
non-electric vehicles must meet the safety requirements in these
FMVSSs. Fire resulting from spillage or leakage of combustible fuels is
addressed in fuel specific FMVSSs, including FMVSS No. 301, ``Fuel
system integrity,'' and FMVSS No. 303, ``Fuel system integrity of
compressed natural gas vehicles,'' by limiting combustible fuel
spillage or leakage. For electric vehicles, FMVSS No. 305a addresses
fire safety assessment directly because limiting electrolyte leakage
outside of the battery pack is insufficient to address the risk of fire
from thermal runaway and propagation in the REESS. Further, it may be
difficult to ascertain the origin of a fire observed at the vehicle
level, and exempting fires that may originate in or involve other
vehicle systems would not be beneficial to safety. For these reasons,
the agency is adopting the proposed requirement.
3. Assessing Post-Crash Voltage Measurements
Proposed Requirements
The NPRM proposed that the post-crash voltage measurements in FMVSS
No. 305a would be made between 10 seconds and 60 seconds after impact.
Using the time of impact to define the measurement period avoids a
source of ambiguity present in FMVSS No. 305 and is consistent with the
GTR No. 20 test procedure. The voltage measurement and calculation
methods in the NPRM are otherwise the same as those currently in FMVSS
No. 305.
Comments Received
Comments on the voltage measurement procedure were mixed, with some
commenters in agreement and others requesting changes to the test
specifications. Manufacturers Nikola, Tesla, and Lucid agreed with the
agency's rationale and stated support for the proposed requirements.
However, Honda said that the timing language is ambiguous and ``could
be misinterpreted to mean that the requirements must be met both at 10
seconds and 60 seconds after the impact.'' Honda also said that 60
seconds is insufficient for isolation resistance measurements and
requested full alignment with GTR No. 20, which does not include the
upper time limit for electrical isolation. Auto Innovators provided a
similar comment, noting that electrical isolation is stable and
requesting removal of the 60-second limit for post-crash isolation
measurements.
Auto Innovators commented on the proposed calculation method as
well, stating, ``the NPRM assumes that V1+V2=Vbat, but this may not be
strictly true,'' due to multimeter resistance. Auto Innovators provided
revised diagrams and formulas and suggested that FMVSS No. 305a provide
an electrical isolation compliance option matching ECE 100.03. Bugatti
also disagreed with the calculation method for the electrical isolation
baseline measurement, saying that it does not address a potential zero-
volt measurement across Ro that may occur if Ri is much higher. Bugatti
noted that the proposed requirements do not allow the use of a
megohmmeter as an alternative method to avoid the zero-volt issue.
Bugatti requested clarification and recommended adding the megohmmeter
measurement method allowed by ECE 100.03. As with the low energy option
for capacitors, Eaton again suggested adding acceptability criteria for
battery isolation.
Agency Response
The agency is adopting the proposed requirements with a minor
revision for the timing of voltage measurements for assessing
electrical isolation post-crash. The proposed requirements stated that
the post-crash voltage measurements would be made ``between 10 to 60
seconds after impact.'' The agency believes that this language is clear
but agrees that the time specification should distinguish between
compliance options. The post-crash electrical safety requirements
include four compliance options: low voltage, electrical isolation,
protective barrier, and low energy for

[[Page 104329]]

capacitors. After further consideration, the agency agrees that the 60-
second time limit is unnecessary for the electrical isolation
measurement procedure because the values are static and that
harmonization with the GTR No. 20 specification is appropriate. For
these reasons, the post-crash test specification has been modified to
state that the measurements for the electrical isolation compliance
option are made at least 10 seconds after impact, with no upper time
limit.
With regard to possible zero-volt measurements in the electrical
isolation baseline calculation, the agency does not believe there is an
issue. Consistent with GTR No. 20, the minimum resistance of the
voltmeter is specified, and a higher resistance R0 can be used if the
voltage measurement is very low. The agency has not observed zero-volt
measurements in testing using the specified procedures, which were
evaluated for practicability and repeatability. The megohmmeter option
from UNECE R100 is not incorporated because research has shown that the
megohmmeter method may provide different results than the multimeter
method. The agency believes inclusion of the megohmmeter option could
lead to inconsistent results and would not be beneficial.
Auto Innovators provided an alternate measurement method and
calculations for electrical isolation resistance that takes into
consideration the resistance of the multimeter used for voltage
measurements. Auto Innovators noted that this alternate method is in
ECE R.100.03 and requested harmonizing with ECE R.100.03. However, the
test method and calculations in ECE R.100.03 \21\ are the same as those
currently in FMVSS No. 305 and proposed in the NPRM for FMVSS No. 305a.
Regardless, the agency will continue evaluating the recommended
alternate procedure to determine whether the results and ease of
testing support its inclusion in FMVSS No. 305a. The alternate method
was not proposed in the NPRM and is therefore out of scope of this
rulemaking. If the agency's research supports use of the alternate
measurement procedure and calculations, they may be added at a later
date. At this time, NHTSA is adopting the method currently in FMVSS No.
305 and proposed in the NPRM for inclusion in FMVSS No. 305a.
---------------------------------------------------------------------------

\21\ See Annex 5A on page 40 in ECE R.100.03 at <a href="https://unece.org/sites/default/files/2024-01/R0100r3e.pdf">https://unece.org/sites/default/files/2024-01/R0100r3e.pdf</a>.
---------------------------------------------------------------------------

The suggestion to add acceptability criteria for battery isolation
to the post-crash requirements was discussed earlier in Section IV.b.1,
``Low Energy Option for Capacitors.''
4. Electrolyte Leakage
Proposed Requirements
The NPRM proposed to include a post-crash requirement limiting
electrolyte leakage; this requirement is currently in FMVSS No. 305 as
``electrolyte spillage'' and permits no more than 5 liters of
electrolyte spilled or leaked. NHTSA sought comment on the necessity
and relevance of such a requirement for current EVs, as well as
recommendations regarding electrolyte leakage detection methods and
differentiation from other liquids.
Comments Received
Commenters agreed that the updated terminology of ``electrolyte
leakage'' is appropriate but stated that the 5-liter maximum leakage
requirement is no longer relevant. Auto Innovators and Nikola both said
that leakage outside of the battery pack should not occur with modern
EVs and that 5 liters is a very large amount. Auto Innovators stated
that there is no reliable method to detect or quantify leakage and
recommended that the requirement be removed entirely. Tesla stated that
physical characteristics can be used to determine whether electrolyte
or coolant has leaked from the vehicle if differentiation is a concern.
Nikola suggested that any electrolyte leakage outside of the battery
pack should constitute a failure. Blue Bird noted that there are many
different forms of electrolytes, including solids and gels, and leakage
may not be observed.
Agency Response
This final rule adopts the updated ``electrolyte leakage''
terminology and the current FMVSS No. 305 requirement for no more than
5 liters of electrolyte leakage post-crash. The cells of lithium-ion
batteries in current EVs have small quantities of electrolyte that
could leak out of the battery casing rather than spill. The agency
agrees with commenters that any electrolyte leakage in EVs using
lithium-ion batteries would be significantly lower than the current 5-
liter limit in FMVSS No. 305. However, there are other types of
batteries with aqueous electrolyte that may be considered for vehicle
applications in the future.\22\ At this time, it is unclear whether the
5-liter limit will remain appropriate for future batteries.
Specifically for vehicles using a REESS with aqueous electrolyte, GTR
No. 20 similarly includes a requirement limiting electrolyte leakage to
no more than 5 liters within 60 minutes after the crash test.\23\
Because there is no further information available, the agency is
adopting the post-crash electrolyte leakage limit of 5 liters that is
consistent with the current requirements in FMVSS No. 305 and GTR No.
20. However, unlike GTR No. 20, the agency is not distinguishing
between REESS with different types of electrolyte; the requirements in
FMVSS No. 305a are established as battery chemistry-neutral and are
applicable to all types of REESS. The agency will continue to review
and update the requirements in FMVSS No. 305a over time, as relevant
information becomes available.
---------------------------------------------------------------------------

\22\ Sodium ion aqueous batteries (SIAB), which are
environmentally benign, provide a promising alternative for safe,
cost-effective, and scalable energy storage, with high power
density. However, current SIABs have limited output voltage and
inadequate energy density for vehicle applications.
\23\ GTR No. 20 also requires that no more than 7 percent by
volume of the REESS electrolyte shall leak into the passenger
compartment. However, as noted in the NPRM, there is no practical
way of measuring the quantity by volume of the electrolyte in the
REESS to ensure compliance with such a requirement.
---------------------------------------------------------------------------

While one commenter suggested a requirement for no electrolyte
leakage outside of the battery pack, a post-crash requirement
prohibiting any electrolyte leakage from the pack was not proposed in
the NPRM and is out of scope for this final rule. A post-crash test
requirement prohibiting any amount of leakage outside of the battery
pack may also be challenging to verify. However, as in FMVSS No. 305,
this final rule includes a requirement that no visible trace of
electrolyte shall leak into the passenger compartment of the vehicle
for occupant safety. This final rule also adopts visual inspection
requirements in the tests evaluating safety during normal vehicle
operations, including no evidence of electrolyte leakage or venting
(without disassembly of the vehicle), as discussed in Section IV.c.6.,
below.

c. Vehicle Controls for Safe REESS Operation

Overview
The NPRM proposed requirements and associated full-vehicle tests
for vehicles to ensure they have controls managing safe REESS
operation, specifically overcharge, over-discharge, overcurrent, over-
temperature, and external short-circuit protection. These requirements
are applicable to light vehicles and heavy vehicles, and are generally
aligned with those in GTR No. 20, with minor differences for ease of
testing. The NPRM also proposed documentation requirements for low-
temperature protection, as in GTR No.

[[Page 104330]]

20, because no practical test procedure currently exists.
Commenters addressed a variety of topics related to the
requirements for safe REESS operation. The comments submitted by NTSB
and Consumer Reports expressed appreciation and support for the
requirements to ensure REESS safety and longevity. The comments from
industry also expressed general agreement with the requirements for
safe REESS operation but disagreed about certain aspects of the test
procedures. Specifically, these comments addressed vehicle- and
component-level testing, REESS state of charge, breakout harness
location, over-temperature testing, overcurrent protection, and venting
and visual inspection, as detailed below. Overall vehicle- and
component-level testing is addressed below in section IV.c.1. Comments
on specific testing provisions for vehicle controls are then addressed
in sections IV.c.2 through c.6.
1. Vehicle- and Component-Level Testing
Proposed Requirements
The NPRM proposed vehicle-level testing using a breakout harness
connected to a battery tester/cycler to evaluate vehicle controls for
safe REESS operation. The test procedures ensure the vehicle controls
provide protection against overcharge, over-discharge, overcurrent,
over-temperature, and external short-circuit fault conditions.
Maintaining the REESS within the manufacturer-specified functional
range minimizes the risk of fire and electrical shock. NHTSA proposed
vehicle-level testing of the REESS because testing at the equipment
level would not evaluate all relevant vehicle controls or any
interaction or interference between vehicle controls.
Comments Received
Many comments from industry disagreed with the agency's exclusion
of component-level compliance test options, which are included in GTR
No. 20 and ECE R100.03. Auto Innovators, Bugatti, EMA, Ford, Honda,
Hyundai, Lucid, NFA, Nissan, UL Solutions, and ZETA were among those
that requested component-level testing. ZETA stated that manufacturers
``could face hurdles in transitioning to vehicle-level testing,
including changing logistics, higher costs, and lack of testing
equipment availability.'' Auto Innovators likewise said that vehicle-
level testing would add significant cost without increasing robustness
or stringency.
Ford agreed with Auto Innovators, saying that it does not have
large enough facilities, and noted that NHTSA did not provide data
showing a need for full-vehicle testing. Honda stated that vehicle-
level testing requires specialized parts, increases safety risks, and
reduces control over test conditions compared to component-level
testing. NFA said requiring full-vehicle testing would be burdensome
and redundant, because the same pack would be tested multiple times.
Hyundai said that the option to conduct testing at the component level
would enable manufacturers to iterate on REESS design and safety
systems more rapidly. Lucid said, ``testing at the component level
(REESS) provides the benefit of recreating the worst-case scenario,
ideal for safety testing, due to its smaller thermal mass. Vehicle-
level testing would also require larger thermal shock chambers than
currently used at the REESS-level.'' UL Solutions also suggested adding
UL 2580 certification as another compliance option, while ZETA further
requested that NHTSA allow manufacturers to specify their own boundary
conditions for component-level testing because each vehicle model is
different.
A few commenters suggested that component-level testing should be
allowed under certain conditions or for specific tests. Nissan
suggested that NHTSA allow a component-level compliance option if the
manufacturer can demonstrate that the test results reasonably reflect
the safety performance of the complete REESS under the same conditions.
UL Solutions similarly requested that the agency ``allow independent
testing of the battery if the battery can demonstrate compliance to the
requirements without the benefit of the vehicle support systems.''
Tesla agreed with most of the proposed test procedures but requested a
component-level compliance option for the over-temperature test, as
``it would be difficult to characterize real-world driving temperature
profiles fully and accurately due to variable drive states.'' Nikola
stated that vehicle-level testing for overcharge, over-discharge, and
over-temperature protection cannot be conducted on hybrid or fuel cell
EVs, so those tests should be conducted at the component level.
Agency Response
After reviewing the comments, the agency is adopting the
requirements as proposed because vehicle-level testing is supported by
NHTSA's research for its practicability and feasibility. NHTSA-funded
research independently evaluated, refined, and validated the proposed
vehicle-level test procedures for various types of electric vehicles
(HEV, PHEV, and BEV).\24\ NHTSA conducted additional research to
evaluate capabilities in compliance test laboratories and
practicability of vehicle level tests.\25\ The test program
demonstrated the ease of conducting tests at the vehicle level using
breakout harnesses connected to a battery cycler/tester for the
external inputs to the REESS without having to remove the REESS from
the vehicle to conduct component-level tests. Evaluating REESS
operation at the vehicle level is consistent with other FMVSSs and
ensures the entire system is captured, including input from different
subsystems and any interaction or interference between vehicle
controls, and is most representative of real-world conditions. A
vehicle level test also ensures that the boundary conditions are
appropriate and would not be challenged in the event of a compliance
test failure. NHTSA's initial research for test procedure development
for electric vehicles was done with the whole vehicle and not with
individual components in the vehicle.\26\ The comments did not
demonstrate that component-level testing of the REESS would provide the
same comprehensive evaluation, nor that full-vehicle tests cannot be
conducted on all applicable vehicles.
---------------------------------------------------------------------------

\24\ System-Level RESS Safety and Protection Test Procedure
Development, Validation, and Assessment-Final Report,'' DOT HS 812
782, <a href="https://rosap.ntl.bts.gov/view/dot/42551">https://rosap.ntl.bts.gov/view/dot/42551</a>.
\25\ Test reports and laboratory test procedures are available
in the docket NHTSA-2021-0029. <a href="https://www.regulations.gov/docket/NHTSA-2021-0029/document">https://www.regulations.gov/docket/NHTSA-2021-0029/document</a>, Docket ID, NHTSA-2021-0029-0001, NHTSA-
2021-0029-0002, and NHTSA-2021-0029-0003.
\26\ Safety Performance of Rechargeable Energy Storage Systems,
DOT HS 812 717, 2019, <a href="https://rosap.ntl.bts.gov/view/dot/40791">https://rosap.ntl.bts.gov/view/dot/40791</a>.
---------------------------------------------------------------------------

In contrast to comments that vehicle-level tests are burdensome,
overly costly, and require additional safety measures, NHTSA's testing
program revealed the ease of conducting testing at the vehicle level
multiple times on the same vehicle without significant cost. The
overcharge, over-discharge, overcurrent, over-temperature, and external
short-circuit test procedures in FMVSS No. 305a are non-destructive,
are conducted at ambient temperatures, and can be conducted
sequentially on the same vehicle, minimizing the time and cost of
testing. The tests also include multiple end conditions for design
flexibility. The agency maintains that the requirements are appropriate
to replicate and confirm real-world vehicle operations and do not
constitute an undue burden on manufacturers.

[[Page 104331]]

We understand manufacturers may conduct testing for various
scenarios beyond the requirements of FMVSS No. 305a, and such testing
may be conducted at the vehicle level and/or the component level.
FMVSSs establish minimum safety requirements and the FMVSS test
procedures provide notice to establish how the agency would verify
compliance. However, this does not mean that manufacturers must conduct
the exact test in the FMVSS to certify their vehicles. The Safety Act
requires manufacturers to ensure their vehicles comply with all
applicable FMVSSs and to certify compliance of their vehicles with all
applicable FMVSSs, and the Safety Act specifies that manufacturers may
not certify compliance if, in exercising reasonable care, the
manufacturer has reason to know the certificate is false or misleading.
A manufacturer may use component-level tests to certify its vehicles if
they exercise reasonable care in doing so. In other words, a
manufacturer must ensure that its vehicles will meet the requirements
of FMVSS No. 305a when NHTSA tests the vehicles in accordance with the
test procedures specified in the standard, but the manufacturer may use
different test procedures to do so.
2. State of Charge (SOC)
Proposed Requirements
Initial SOC ranges were specified for each of the proposed test
procedures for vehicles to ensure they have controls managing safe
REESS operations. Some of the SOC ranges differed from those in GTR No.
20 for practicability and ease of conducting the tests. For the
overcharge, over-temperature, and external short-circuit tests, the
REESS is initially at 90 to 95 percent SOC. For the over-discharge
test, the REESS is initially at 10 to 15 percent SOC. For the over-
current test, the REESS is initially at 40 to 45 percent SOC.
Comments Received
Several commenters stated that there should be more flexibility in
the SOC ranges for the tests. Auto Innovators and Honda stated that the
proposed values are too extreme and will likely have already activated
the protections. Auto Innovators requested that NHTSA align the
starting SOC values with those in GTR No. 20. Nissan suggested setting
the starting SOC around the middle of the normal operating range for
the overcharge and external short-circuit tests, as in UNECE Regulation
No.100, because hybrid vehicles may fall outside the range of normal
use if the REESS is initially set between 90 to 95 percent SOC. Bugatti
commented similarly, ``Prescribing absolute values for SoC of the
REESS, without consultation of manufacturer-specified SoC operational
windows, may influence test results due to possible risk for the REESS
to be out of its normal operating SoC range, even from the beginning of
tests.'' Bugatti recommended removing SOC values and taking a similar
approach to UNECE Regulation No. 100, which references manufacturer-
specified SOC.
Agency Response
After reviewing the comments, the agency is adopting the proposed
requirements with a minor modification to the definition of SOC to
clarify the requirements and address commenters' concerns. The initial
SOC specifications in the test procedures refer to the ``operating
SOC,'' or percent charge available under normal operation as it may be
displayed to the user. In other words, the charge level for beginning
each test is based on the normal functional range of the REESS defined
by the manufacturer, not direct measurement of the battery capacity.
This distinction was not sufficiently clear in the NPRM, leading to
concerns about the validity of the test parameters. However, the
specified parameters were tested and validated for different types of
electric vehicles, including HEV and PHEV. These tests included vehicle
crash tests of battery electric vehicles \27\ and tests of vehicle
controls that manage REESS operations and its health.\28\ The initial
SOC ranges are intended to minimize the amount of time needed to
conduct each test. Starting every test in the middle of the normal
operating range rather than the upper or lower portion would lead to
longer test times with no added benefit. In the event that the vehicle
does not display the operating SOC, the charge level can be estimated
using the information provided by the manufacturer.
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\27\ As an example, see page 2-27 of a NCAP crash test report of
the 2022 Chevrolet Bolt, which indicates that the voltage range
corresponds to the ``usable energy'' of the battery. <a href="https://nrd-static.nhtsa.dot.gov/reports/vehdb/v10000/v14200/v14218R001.pdf">https://nrd-static.nhtsa.dot.gov/reports/vehdb/v10000/v14200/v14218R001.pdf</a>.
\28\ Electric Vehicle GTR No. 20 Test Development, Validation,
and Assessment, DOT HS 812 092, April 2021, <a href="https://rosap.ntl.bts.gov/view/dot/55584">https://rosap.ntl.bts.gov/view/dot/55584</a>.
---------------------------------------------------------------------------

To improve clarity, NHTSA is changing the definition of ``State of
charge'' to mean the available electrical charge in a REESS expressed
as a percentage of the normal operating capacity specified by the
vehicle manufacturer.
3. Breakout Harness Location
Proposed Requirements
The NPRM proposed to conduct the REESS tests using a breakout
harness connected to manufacturer-specified location(s) on the traction
side of the REESS on the vehicle's electric powertrain. The
manufacturer is required to specify the location(s) for connecting the
breakout harness and may also provide an appropriate breakout harness
for testing the vehicle. If the manufacturer does not provide a
breakout harness, NHTSA will use a generic breakout harness to connect
to the traction side of the REESS.
Comments Received
Regarding the overcharge, over-discharge, and overcurrent test
procedures, Honda stated that the term ``traction side'' is too
prescriptive and inconsistent with the proposed test procedure in
S12.5, which did not include the same specification. Auto Innovators
provided the same comment. Prevost requested clarification of the
``traction side'' designation to make clear which systems and
subsystems are considered to be part of the traction side of the REESS
and which are not. An example to clarify is whether the charging inlet
is part of the ``traction side'' of the REESS. Prevost further
suggested making note of a designated location when it is not specified
by the manufacturer.
Agency Response
This final rule adopts the proposed requirements for the breakout
harness location(s) as described in the NPRM, with edits for clarity
and consistency. The ``traction side'' of the REESS refers to the
connection between the REESS and the transmission, so it does not
include the charging inlet. The traction side of the REESS is specified
to ensure that external charging and regenerative charging are both
captured by the test. Regenerative charging can potentially lead to
overcharge conditions even if the vehicle controls prevent overcharging
from the charging inlet. The manufacturer is also required to state the
connection location(s) because a single location would not work for all
vehicles and because connecting the harness to the wrong points of the
powertrain could be damaging and/or hazardous. For the test operators'
safety, ease of testing, and to prevent damage to the vehicle or test
equipment, the manufacturer is required to recommend specific
connection location(s). Although the NPRM clearly stated that the
manufacturer is required to provide connection locations, the proposed

[[Page 104332]]

regulatory text was inconsistent. The text in S12 has been edited to
clarify the requirement. Additionally, because the manufacturer is
required to provide connection locations, no default locations are
necessary. Regarding the exclusion of ``traction side'' in S12.5, that
test is intended to evaluate the response to an external short circuit,
so the traction side specification does not apply. Another possible
source of confusion could be due to the proposed text for S12.5
referencing ``overcharge'' instead of ``external short-circuit;'' the
text has been corrected in the final rule.
4. Over-Temperature Protection
Proposed Requirements
The NPRM proposed to include the over-temperature protection
requirement and test procedure from GTR No. 20, with minor changes.
NHTSA's testing indicated that presoaking the vehicle was not
necessary,\29\ so the NPRM proposed to remove presoaking from the
procedure to reduce the test time and burden. The test procedure
specifies that the test is conducted at ambient temperature, between
10[deg]C and 30[deg]C, with the cooling system disabled or minimized.
The vehicle is driven on a chassis dynamometer using the manufacturer-
provided drive profile, or with aggressive acceleration and
deceleration if an appropriate drive profile is not provided.
---------------------------------------------------------------------------

\29\ NHTSA testing demonstrated that presoaking of the vehicle
at elevated temperature does not raise the temperature of the REESS
as significantly as by driving the vehicle under high acceleration
and deceleration drive modes. See System-Level RESS Safety and
Protection Test Procedure Development, Validation, and Assessment-
Final Report. DOT HS 812 782 October 2019. <a href="https://rosap.ntl.bts.gov/view/dot/42551">https://rosap.ntl.bts.gov/view/dot/42551</a>.
---------------------------------------------------------------------------

Comments Received
Commenters generally agreed with the requirement but recommended
changes to some aspects of the test procedure. MEMA stated agreement
with the agency's decision to remove presoaking, and Auto Innovators
agreed with removing the requirement but said it should be permitted.
Auto Innovators also stated that several provisions were overly
prescriptive and unnecessary, specifically the directions to conduct
the test on a chassis dynamometer and/or in active driving mode, limit
the ambient temperature to 30[deg]C, and specify a one-hour time
period. Honda also disagreed with the limits on the time period and
ambient temperature, stating that there are situations where the
battery temperature will not rise unless the ambient temperature rises.
EMA also suggested modifying the standard cycle specification to allow
a manufacturer supplied drive profile, as ``S12.4 (d) requires using an
appropriate manufacturers supplied drive profile and (h) should follow
the same drive profile or allow for the option to follow the same
manufactured supplied drive profile.'' In an ex-parte meeting,\30\
Nissan commented that it was unclear whether all three test termination
conditions had to be fulfilled to terminate the charge/discharge cycle.
---------------------------------------------------------------------------

\30\ Nissan requested to meet with NHTSA to present information
related to the proposed rule. An ex-parte memo has been submitted to
the docket (<a href="https://www.regulations.gov/docket/NHTSA-2024-0012">https://www.regulations.gov/docket/NHTSA-2024-0012</a>).
---------------------------------------------------------------------------

Agency Response
After reviewing the comments, the agency is adopting the proposed
requirements with an additional clarification for the manufacturer-
provided drive profile. The proposed rule defined an appropriate drive
profile by stating that it should raise the temperature of the REESS
above the safe operating temperature within one hour. The test
procedure specifies that the cooling system is disabled or functionally
minimized for testing, but this provision was not stated when defining
an appropriate drive profile. The commenters did not specify if the
REESS cooling system was minimized in their testing. However, the
agency recognizes that some vehicles may not be operable with cooling
reduced to a level that would allow the REESS to overheat under the
specified test conditions. To address commenters' concerns, if it is
not possible to raise the temperature of the REESS without raising the
ambient temperature of the vehicle above 30[deg]C, the manufacturer may
provide a drive profile that would trigger the over-temperature
condition within one hour if the thermal management system were
effectively disabled.
For the performance test, the test termination conditions in FMVSS
No. 305a are identical to those in GTR No. 20, where the vehicle may be
charged and discharged for up to 3 hours. The test time is not limited
to one hour and it is not required to trigger the over-temperature
protection, to avoid penalizing effective thermal management. The test
procedure also does not prohibit presoaking or otherwise specify the
starting temperature of the vehicle. However, the test is conducted at
ambient temperature to avoid the added cost of testing in a heat
chamber. The use of a chassis dynamometer and active driving possible
mode of the vehicle are specified to ensure that the vehicle is tested
in the normal operating state. The termination conditions were
accurately described in the preamble of the NPRM and are the same as
those in GTR No. 20. However, the agency agrees that the proposed
regulatory text did not clearly indicate only one of the termination
conditions needs to be fulfilled to terminate the discharge/charge
cycle. The regulatory text specifying the test methods for evaluating
vehicle controls managing REESS safe operations (S12) have all been
modified to clarify the corresponding termination condition
requirements in the final rule.
Section S12.4(h) of the over-temperature test procedure specifies
conducting a standard cycle, if allowed by the vehicle. A standard
cycle, as defined in GTR No. 20 and FMVSS No. 305a, consists of a
standard discharge followed by a standard charge. The NPRM stated that
the discharge and charge rates used for the standard cycle would be
provided by the vehicle manufacturer. It also specified the alternative
charge and discharge rates that would be used if the manufacturer did
not provide them. The standard cycle is the same for each of the test
procedures addressing safe operation of the REESS and is unrelated to
other test specifications. The definition and use of the standard cycle
are adopted as proposed.
5. Overcurrent Protection
Proposed Requirements
The NPRM proposed to include the overcurrent protection and test
for vehicles capable of charging by direct current (DC) external
electricity supply, as in GTR No. 20. During the test, the REESS is
charged using the battery tester/cycler in accordance with the
manufacturer's recommended charging procedure with the highest normal
charge current specified by the manufacturer, or at a rate of C/3
current if none is provided. After charging is initiated, an over-
current specified by the manufacturer is supplied, or the current is
increased in 10-Ampere steps, until the vehicle over-current protection
terminates charging or the temperature gradient of the REESS is within
4[deg]C for a two-hour period. The standard cycle is then performed, if
possible, and the test concludes with electrical isolation assessment
and a one-hour observation period to assess evidence of electrolyte
leakage, venting, fire, or rupture.
Comments Received
EDTA, MEMA, NEMA, and Eaton suggested expanding the overcurrent
protection requirements to address battery isolation. NEMA said that
the

[[Page 104333]]

contactors can weld, leading to a system protection failure and a
safety issue, and that GTR No. 20 does not offer adequate overcurrent
protection in those cases. Eaton emphasized that contactor failure
occurs frequently, as evidenced by recent vehicle recalls, and
suggested NHTSA require manufacturers to demonstrate they can fully
isolate the positive and negative poles of the battery following a
vehicle crash or overcurrent event. EDTA, MEMA, and NEMA made similar
comments, requesting battery isolation testing and documentation
showing no single point of failure.
Agency Response
After reviewing the comments, the agency is adopting the proposed
requirements. NHTSA agrees with commenters that contactor failure can
lead to system protection failure and a safety issue. However, we do
not see a need to explicitly require ``fully isolat[ing] the positive
and negative poles of the battery following a vehicle crash or
overcurrent event,'' as Eaton and other commenters suggested. The test
procedures in the FMVSS are established to mitigate safety risks in a
manner that is not design restrictive. In the adopted overcurrent test,
the overcurrent is applied until either the protection controls
terminate charging (contactors open), or a long time has passed without
an appreciable change in REESS temperature. Additionally, after the
overcurrent is applied, a standard cycle is performed, if possible,\31\
after which no electrolyte leakage, rupture, venting, fire, or
explosion is permitted during a one-hour observation period. At the
conclusion of the observation period, the electrical isolation is
determined in a similar manner as in FMVSS No. 305, using a voltmeter
to measure the voltages. The agency believes that the termination
criteria for the application of overcurrent and the subsequent
evaluations ensure that the main contactors in the REESS are not fused
due to the overcurrent and therefore mitigate the safety risk. These
requirements are intended to enhance safety while allowing
manufacturers design flexibility.
---------------------------------------------------------------------------

\31\ If the contactor opens when the overcurrent is applied, the
vehicle will not charge/discharge unless the controls are reset.
---------------------------------------------------------------------------

NHTSA will continue to research and assess electric vehicle safety
issues and the need for additional changes to the overcurrent
requirements. NHTSA is also aware of vehicle fires originating at the
vehicle charge inlet while the vehicle is being charged. Some of these
fires have resulted from faulty connections between the charge
connector and the vehicle. As part of NHTSA's Battery Safety
Initiative,\32\ the agency continues to evaluate these safety risks and
potential future agency actions to mitigate these risks.
---------------------------------------------------------------------------

\32\ <a href="https://www.nhtsa.gov/battery-safety-initiative">https://www.nhtsa.gov/battery-safety-initiative</a>.
---------------------------------------------------------------------------

6. Venting and Visual Inspection
Proposed Requirements
Venting is the release of excessive internal pressure from a cell
or REESS in a manner intended by design to preclude rupture or
explosion. Venting during normal vehicle use may result in varying
degrees of safety risks to the vehicle occupant. The NPRM proposed that
each of the tests evaluating vehicle controls for safe REESS operation
(overcharge, over-discharge, overcurrent, over-temperature, and
external short-circuit test procedures) would end with the vehicle
observed for one hour for evidence of electrolyte leakage, rupture,
venting, fire, or explosion, followed by voltage measurements for
determining electrical isolation. NHTSA proposed that there be no
evidence of electrolyte leakage, venting, or rupture that is verified
by visual inspection without disassembly of any part of the vehicle.
Visible smoke during and after the test, and/or the presence of soot
and/or electrolyte residue in post-test visual inspection, are
indicators of venting and electrolyte leakage. The agency acknowledged
that research is needed to develop a repeatable, reproducible, and
practical method to verify the occurrence of various vented gases and
requested comment on the Informal Working Group's continuing work in
Phase 2 of the GTR.
Comments Received
As a whole, commenters agreed that venting detection methods are
challenging to specify at this time and appropriate sensors are still
under development. Auto Innovators stated that the proposed visual
inspection requirement is unnecessary because visible venting is
unlikely. On the other hand, DTNA agreed with the visual inspection
requirement but requested adding a test procedure provision where
venting inspection is captured visually and with written description of
the findings.
With regard to sensor research, Tesla stated agreement with the
agency's assessment that more research is needed, and Nikola said it
doesn't have enough to data to recommend the usage of such sensors for
general application. For future test requirements, Rivian suggested
that the detection method depend on whether the area of concern is the
gas venting within the REESS or the risk of occupant/bystander exposure
to vented gases. Rivian noted that gas detection outside of the REESS
is more challenging than detection inside the REESS and recommended
prioritizing carbon monoxide sensors. Auto Innovators suggested
focusing on a limited number of critical gases, with an emphasis on
release or venting that may impact occupants.
Agency Response
The agency is adopting the proposed requirements for no evidence of
electrolyte leakage, rupture, venting, fire, or explosion as determined
by visual inspection during a one-hour observation period for each of
the vehicle controls for safe REESS operation tests. The commenters
agreed that appropriate sensors and procedures for detection of vented
gases are not currently available and that more research is needed.
NHTSA is continuing to investigate gas detection methods and potential
test procedures to address venting of hazardous gases such as carbon
monoxide. This research will inform future rulemaking. At this time,
the agency believes inclusion of the visual inspection requirement
enhances safety protection to limit safety risk to vehicle occupants
due to venting and should remain a minimum requirement until
quantitative detection methods are fully developed. As with similar
standards, the compliance test procedures will include recording of the
visual inspection results, using detailed descriptions, video, and/or
photographs as appropriate.

d. Mitigating Risk of Thermal Propagation Due to Internal Short Within
a Single Cell in the REESS

Proposed Requirements
The NPRM proposed documentation requirements for risk mitigation of
thermal propagation events resulting from single-cell thermal runaway
(SCTR) due to an internal short circuit within a cell in the REESS.
NHTSA's proposed documentation component structure is based on elements
from GTR No. 20, ISO-6469-1: Amendment 1

[[Page 104334]]

2022-11,\33\ and ISO-26262.\34\ The documentation submitted by the
manufacturer is required to include all known risks to vehicle
occupants and bystanders, risk assessment, risk management, and risk
mitigation strategies in external charging mode, active driving
possible mode, and parking mode. The objective of the documentation
requirements is for vehicle manufacturers to identify the risks of
single-cell thermal runaway and propagation for their REESS type,
identify strategies to mitigate those risks, and demonstrate how those
strategies work. The manufacturers' assessment and validation of risk
mitigation strategies may involve a combination of physical testing and
simulations at the component level and/or full vehicle level. The
requirements are not design restrictive and apply to REESSs of all
types.
---------------------------------------------------------------------------

\33\ ISO 6469-1: Third Edition 2019-04 Amendment 1 2022-11,
``Electrically propelled road vehicles--Safety specifications--Part
1: Rechargeable energy storage system (RESS),'' specifies safety
requirements for REESSs, including test methodology for initiating
thermal runaway in a cell for the purpose of conducting a thermal
runaway propagation test and a format for reporting on risk
mitigation strategies of thermal propagation resulting from a
thermal runaway in a single cell of an REESS due to an internal
short within the cell.
\34\ ISO 26262: 2018, ``Road vehicles--Functional safety,''
provides a comprehensive collection of standards to manage and
implement road vehicle functional safety from concept phase to
production and operation. The standard provides guidelines for
overall risk management, individual component development,
production, operation, and service.
---------------------------------------------------------------------------

Comments Received
There were several comments on SCTR risk mitigation documentation,
including multiple requests for clarification. Tesla, HATCI, and
Honeywell stated support for the proposed documentation approach.
However, HATCI disagreed with the addition of the two new operation
modes, stating they are unlikely to add material safety benefits while
unnecessarily increasing the test and documentation burden, whereas
Honeywell said the addition acknowledges the need to identify distinct
risks and mitigations for each operational mode. Nissan suggested that
NHTSA add a detailed description of safety risks ``such as fire,
explosion, or smoke'' to enhance clarity regarding the severity of
these risks in S13.1. Lubrizol stated strong support for the
requirements proposed in the NPRM and provided graphs demonstrating the
performance of their fluids for immersed thermal management of the
REESS.
Auto Innovators questioned the necessity of the SCTR requirement
given the inclusion of other thermal runaway and propagation
requirements (e.g., the requirement for a thermal event warning), and
asked the agency to provide additional research to support the
inclusion of this requirement, though it also said that the proposed
reporting requirements appear to be reasonable. Additionally, Auto
Innovators said the requirement should not apply to Ni-MH batteries
because the electrolyte generally used in Ni-MH batteries is not
flammable; Auto Innovators noted that GTR No. 20 and industry standards
limited the requirement to flammable electrolyte REESS and that
internal short-circuits are less likely in Ni-MH batteries due to
greater spacing of the electrodes. Auto Innovators further requested
clarification on several aspects of the requirements, including risks,
validation strategies, and terminology where the FMVSS deviates from
GTR No. 20. Auto Innovators said the term ``vehicle power'' in the
definition of parking mode is ambiguous and could mean any voltage or
just high voltage. Auto Innovators also said there should be processes
for updates or corrections, the requirements should not be limiting,
and providing confidential business information should not be required
if the information is subject to public disclosure.
Lucid and NFA also requested further clarification of the
requirements. Lucid said, ``As proposed, the requirements could lead to
either over- or under-reporting. Lucid stresses the importance of
delineating the documentation requirement under Part IV, overall
evaluation of risk mitigation, to avoid conflation with risk mitigation
itself.'' NFA likewise suggested that NHTSA define ``the requisite
detail level within the SCTR Risk Assessment and Mitigation
documentation of the Proposal, with the expectation that it aligns with
established best practices and industrial standards, such as ISO 26262
or SAE J1739.'' NFA also stated that the vehicle manufacturers will
need information from the REESS manufacturer and NHTSA should follow
the confidential document treatment procedure of 49 CFR part 512 to
protect proprietary information. Nikola agreed that it makes sense to
not require a warning for SCTR and that a thermal runaway warning
should be required. Nikola suggested a battery manufacturer requirement
similar to the UL 2580 SCTR test, which forces a cell into thermal
runaway. Similar to NFA, Nikola expressed concerns about obtaining
proprietary information from battery manufacturers and suggested
Confidential Business Information treatment per 49 CFR part 512.
Agency Response
For the final rule, the agency is adopting the proposed risk
mitigation documentation requirements. However, instead of including
the documentation requirements in FMVSS No. 305a as proposed, this
final rule includes the risk mitigation documentation requirements in
part 561. The purpose of these documentation requirements is to ensure
that manufacturers have considered and addressed the risk of SCTR due
to an internal short circuit, as the risk is highly dependent on REESS
design and there is no one field-relevant performance test that can be
applied to all REESS designs in a repeatable and reproducible manner.
NHTSA-funded research examined various existing methods of initiating
thermal runaway, including the heating element method, rapid heater
method, nail penetration, and laser method, on batteries with a variety
of chemistries, formats, and configurations.\35\ The agency's research
indicated that the thermal runaway initiation methods may influence the
test results and the most appropriate initiation method for a battery
may depend on the battery chemistry, format, and configuration. Nikola
referenced a private industry developed standard, UL 2580 ``Standard
for batteries for use in electric vehicles,'' as a potential
requirement for battery manufacturers. Among other requirements, UL
2580 specifies a test where a single cell is forced into thermal
runaway, by any means recommended by the battery manufacturer, with a
requirement for no evidence of fire or explosion for 1 hour after
initiating thermal runaway. Such a test is not appropriate as a
compliance test procedure because some thermal runaway initiation
methods employed may require advanced equipment and knowledge of the
REESS that is only available to the manufacturer. It is also difficult
to establish objectivity and could be design restrictive. However,
manufacturers may voluntarily use any or all of the tests in UL 2580
for validating risk mitigation strategies in their documentation
submitted to the agency. For these reasons, the agency is not requiring
a performance test for thermal runaway of a single cell.
---------------------------------------------------------------------------

\35\ Lamb, J., Torres-Castro, L., Stanley J., Grosso, C, Gray,
L., ``Evaluation of Multi-Cell Failure Propagation,'' Sandia Report
SAND2020-2802, March 2020. <a href="https://www.osti.gov/servlets/purl/1605985">https://www.osti.gov/servlets/purl/1605985</a>.
---------------------------------------------------------------------------

Regarding the need for SCTR risk mitigation requirements given the
other requirements in the proposal, including

[[Page 104335]]

warning for a thermal event in the REESS, the agency believes a
requirement to mitigate the risk of SCTR due to an internal short
circuit is needed because: (1) there have been a number of electric
vehicle fires in the field resulting from a short circuit within a cell
in the REESS of vehicles in parking, charging, and driving modes, (2)
none of the performance test requirements for the safe operation of the
REESS (overcharge, over-discharge, overcurrent, external short-circuit
tests) address SCTR and thermal propagation resulting from an internal
short circuit, and (3) the thermal event warning is required when the
vehicle is in the active driving possible mode to allow vehicle
occupants to safely egress, but does not address prevention of vehicle
fire.
With regard to specific battery chemistries, the documentation
requirements for SCTR are battery chemistry neutral. Safety risks need
to be evaluated and mitigated for all types of vehicle REESS,
regardless of chemistry, to minimize the possibility of hazardous
conditions. Gas venting, explosion, or other hazards can occur even
without flammable electrolyte. The documentation requirements include
identification of safety risks and mitigation strategies. If a REESS
uses non-flammable electrolyte and the REESS cells have large spacing
between electrodes, those elements may be included as primary risk
mitigation strategies in the required documentation. Primary risk
mitigation strategies include manufacturing quality control to mitigate
defects in cells of REESS, REESS design features such as heat sinks,
cell spacing, coolant, advanced battery management system with
prognostics, and diagnostics systems to manage the health of the cells
of an REESS and detect a possible thermal runaway condition before it
occurs. Primary risk mitigation strategies reduce the risk of SCTR due
to an internal short circuit and the occurrence of thermal propagation
that may result from SCTR, while secondary risk mitigation strategies
may not reduce the risk of thermal runaway or thermal propagation but
reduce the hazards associated with thermal propagation. Secondary risk
mitigation strategies include warning systems to vehicle occupants/
bystanders and/or notification to emergency personnel in the event of
thermal propagation (e.g., automatic notification to 911 operators).
The NPRM provided examples of mitigation strategies, but specific
strategies are not mandated, allowing flexibility and practicability of
various battery chemistry and battery systems without limiting only
certain risk mitigation strategies known now. The risk reduction
analysis requirement follows industry standard methodology.\36\
---------------------------------------------------------------------------

\36\ ISO 26262, ``Road vehicles--Functional safety,'' provides a
comprehensive collection of standards to manage and implement road
vehicle functional safety from concept phase to production and
operation. The standard provides guidelines for overall risk
management, individual component development, production, operation,
and service. <a href="https://webstore.ansi.org/industry/automotive/electric/safety/functional-safety-iso-26262?psafe_param=1&gad_source=1&gclid=Cj0KCQjw99e4BhDiARIsAISE7P_bipjmLqkehMPUorfq0x2h6lAVWmd0GSbo7Z7qRtwAI-Rfd40YBMUaAuMuEALw_wcB">https://webstore.ansi.org/industry/automotive/electric/safety/functional-safety-iso-26262?psafe_param=1&gad_source=1&gclid=Cj0KCQjw99e4BhDiARIsAISE7P_bipjmLqkehMPUorfq0x2h6lAVWmd0GSbo7Z7qRtwAI-Rfd40YBMUaAuMuEALw_wcB</a>.
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As previously stated, the requirements are based on those from GTR
No. 20. NHTSA extended the requirements to include consideration of the
external charging and parking modes to ensure safety under all normal
vehicle operating conditions. The incremental amount of documentation
from adding other operating modes is minimal. The operating modes were
defined in the NPRM, with Parking mode defined as ``the vehicle mode in
which the vehicle power is turned off, the vehicle propulsion system
and ancillary equipment such as the radio are not operational, and the
vehicle is stationary.'' Per this definition, both the high-voltage and
the low-voltage power are turned off. The regulatory text also
describes the information to include in each section of the
documentation for completeness, from system diagrams to validation of
risk mitigation strategies. As proposed, the required documentation is
to be submitted upon request. Documentation containing proprietary
information can be submitted as Confidential Business Information (CBI)
under 49 CFR part 512 and will be handled accordingly. Documentation
submission, regulations, and CBI are discussed further in Section k.

e. Thermal Event Warning

Proposed Requirements
As part of a risk-mitigation approach addressing multiple aspects
of electrical system safety, the NPRM proposed a performance
requirement for a thermal event warning. The term ``thermal event''
refers to a condition when the temperature within the REESS is
significantly higher (as defined by the manufacturer) than the maximum
operating temperature specified by the manufacturer. Thermal events may
occur due to moisture and dust accumulation that causes a short circuit
at the connections or electronic components within the REESS. A thermal
event within a battery pack can be a safety critical event, as it can
lead to smoke, fire, and/or explosion. A warning provided when a
thermal event within the REESS occurs while the vehicle is in active
driving possible mode would reduce the likelihood of occupant exposure
to hazardous smoke, fire, and/or explosion. NHTSA also proposed that
the visual warnings be provided to all front row occupants for vehicles
with automated driving systems without manually operated driving
controls.
Comments Received
There were many comments on the proposed thermal event warning
test. Comments from Consumer Reports, Lucid, and EMA stated support for
the actual audio-visual warning. Consumer Reports also suggested that
NHTSA work with manufacturers to ensure all warnings are sufficiently
prominent and convey the severity of the event. SAVE Coalition agreed
with the warning overall but noted that it was only directed to the
driver of the vehicle. To include vehicles equipped with automated
driving systems, SAVE Coalition suggested adding, ``For a vehicle
without manually operated driving controls, the warning must be
provided to occupants in all outboard designated seating positions.''
On the other hand, Auto Innovators said, ``We recommend remove
requirements for AVs without manual driving controls; NHTSA has not
provided rationale for why any warning needs to be provided to the
`front row occupant'; the occupant cannot take any action based on the
visual warning.'' Honeywell suggested adding an auditory warning
requirement for active charging and parking modes to enable relocation
of adjacent vehicles, evacuation of building occupants, and alerts to
bystanders. ACIL likewise encouraged NHTSA to include requirements for
a warning to vehicle occupants and/or bystanders outside the vehicle in
the event of thermal propagation.
Some commenters said that the NPRM discussion of ``thermal
runaway,'' ``thermal propagation,'' and ``thermal event'' was unclear.
Nissan suggested that sections S13.2 and S13.3 for the thermal event
warning should be distinct from S13, thermal propagation safety, to
ensure clarity and precision in addressing thermal safety risks within
the documentation. Nikola said, ``NHTSA is proposing to not have a
warning for a thermal runaway but to require one for thermal event that
is intended to inform occupants to egress the vehicle. The definitions
of Thermal event and Thermal Runaway are being

[[Page 104336]]

conflated.'' NFA likewise stated that there appeared to be a
discrepancy in NHTSA's statements about the relevance of SCTR and
thermal event warnings.
Many comments disagreed with the parameters of the proposed test
requirement. Auto Innovators said the NPRM did not provide references
or otherwise explain the test parameters. They noted that battery
modifications can be risky and suggested slower heating due to
``concerns with the proposed test method of using a heater that
abruptly achieves 600C within 30 seconds [which] could result in
unstable test conditions.'' NFA said that the three-minute timeframe
seems arbitrary and uncorrelated with occupant hazard exposure, and
suggested using the SCTR thermal propagation criteria from ECE R100.
Tesla, HATCI, Honeywell, ZETA, Lucid, Nikola, and Honda all expressed
similar concerns over the timing and occurrence of actual thermal
runaway and propagation with the proposed test procedure. Some
suggested other initiation methods or a ramp of 180 seconds as in GTR
No. 20. Nissan said the temperature specification was too high. Honda
recommended clarification that the temperature specification refers to
the heater temperature, not the REESS temperature. Honda also requested
clarification on allowable modifications to the REESS, including
replacement of one or more cells with heater equipment preinstalled for
accurate test results. Similarly, Bugatti requested ``a clear
definition of thermal runaway condition and confirmation whether
instrumented cells will be allowed to recognize this event,'' to ensure
that manufacturers have flexibility to accommodate the test equipment
if NHTSA does not allow other triggering methods.
Several vehicle and component manufacturers said that the vehicle-
level test requirement is unnecessarily dangerous. MEMA said that the
test would generate toxic smoke and other potentially unsafe conditions
for test personnel, and contradicts other requirements to mitigate or
stop thermal runaway. Ford said the heater test is ``unnecessarily
destructive and burdensome in that it requires the initiation of a
thermal runaway to confirm the illumination of a warning light,'' and
recommended verification using an electronic signal instead. Prevost
also expressed safety concerns, noted additional difficulty in testing
heavy vehicles, and suggested a subsystem test. EMA suggested a
documentation requirement or component-level test, as the full-vehicle
test could destroy the vehicle and introduce an unsafe situation. Many
other commenters also recommended implementing the documentation
requirement from GTR No. 20 due to issues with the proposed test
requirement.
Agency Response
After consideration of the comments, the agency is not adopting the
proposed performance test requirement for the thermal event warning but
is implementing a corresponding documentation requirement in part 561
instead. While the agency maintains the importance of the required
thermal event warning, commenters raised concerns about the proposed
test method and safety of testing. The agency agrees that additional
research is needed to ensure that any performance test for the thermal
event warning is well-defined, appropriate for all vehicles, and does
not pose an undue risk to test personnel. In turn, the documentation
requirements are adopted for the final rule.
The documentation requirements for the audio-visual thermal event
warning are similar to those in GTR No. 20. Manufacturers are required
to provide documentation to the agency, upon request, with a detailed
description of the system for triggering the warning. Specifically, the
documentation requirements include parameters and associated threshold
levels that are used to indicate a thermal event (e.g., temperature,
temperature rise rate, SOC level, voltage drop, electrical current,
etc.) to trigger the warning, as well as a system diagram and written
explanation describing the sensors and operation of the vehicle
controls that manage the REESS in the event of a thermal event.
The primary purpose of the adopted warning is to ensure occupants
have sufficient time to exit the vehicle to minimize direct exposure to
potential hazards. The warning is to be provided regardless of the
cause of the thermal event. A thermal event in the REESS can lead to
smoke, fire, and/or explosion, and a warning can reduce the likelihood
of occupant exposure to these safety hazards. The audio-visual warning
is provided to the driver, or to all front row occupants in the case of
autonomous vehicles without manually operated controls, notifying of a
thermal event in the REESS when the vehicle is in active driving
possible mode. The agency believes this specification is appropriate to
ensure the driver or the front row occupants in vehicles with automated
driving systems without manually operated controls are alerted of the
potential safety hazard to ensure the driver or occupants can stop and
exit the vehicle. The front row provision for vehicles with automated
driving systems is aligned with other FMVSSs \37\ and may be revised
over time. The primary purpose of the adopted warning is to ensure
occupants have sufficient time to exit the vehicle to minimize direct
exposure to potential hazards. Activation of a warning to bystanders
outside the vehicle was not proposed in the NPRM and is not in scope
for this final rule. Additionally, further research needs to be
conducted to determine the type and efficacy of such a warning to
people outside the vehicle.
---------------------------------------------------------------------------

\37\ See requirements in S9.2.2 of FMVSS No. 208 with regard to
the air bag suppression telltale. The telltale is required to be
visible to the front outboard passengers.
---------------------------------------------------------------------------

Some commenters said the discussion in the NPRM was unclear between
the term of thermal event and SCTR and the corresponding warning
requirements. Section 2 of the NPRM addressed thermal propagation from
SCTR due to an internal short circuit within the cell; this is a
specific hazard that can be minimized by risk evaluation and mitigation
in design and manufacturing. Risk mitigation includes implementing
strategies to prevent SCTR and to isolate a cell that is in thermal
runaway to prevent thermal propagation. A warning specifically for SCTR
is not required. However, any instance of thermal runaway and
propagation that occurs, regardless of the cause, should trigger the
thermal event warning for the vehicle occupants' safety. To minimize
confusion, the documentation requirements for the thermal event warning
and for SCTR risk mitigation are adopted in separate sections of part
561.

f. Vehicle Control Malfunction Warning

Proposed Requirements
The NPRM proposed a documentation requirement for a driver warning
in the event of a malfunction of vehicle controls that manages the safe
operation of the REESS. The warning documentation requirement is
similar to GTR No. 20, with two added provisions, and is an interim
measure intended to ensure that manufacturers will identify, address,
and validate the effectiveness of their visual warnings that help
manage safe REESS operation. This approach is intended to evolve over
time as battery technologies and NHTSA's information about the REESS
safety risk mitigation strategies evolve.

Comments Received

Comments on the vehicle control malfunction warning documentation
requirement were positive. Nikola

[[Page 104337]]

agreed with requiring a warning, stating that it already provides
malfunction warnings to the driver and documents all the information in
the monitoring and diagnostic documents required by the California Air
Resources Board for powertrains. Tesla stated support for including the
requirements in FMVSS No. 305a because they apply to all REESSs
irrespective of crash conditions. HATCI and Auto Innovators also stated
support for the proposed documentation requirements. Auto Innovators
agreed that there is currently no practical test procedure and stated
support for the documentation approach.
Agency Response
The agency is adopting the proposed requirements for a driver
warning in the event of a malfunction of vehicle controls that manage
the safe operation of the REESS. Commenters agreed that the warning and
documentation requirement are appropriate and indicated that they may
already maintain and produce such documentation as required by other
regulations. For the final rule, the vehicle control malfunction
warning requirements are adopted in FMVSS No. 305a and part 561.

g. Protection Against Water Exposure

Proposed Requirements
The NPRM proposed water exposure test requirements, where a vehicle
shall maintain electrical isolation resistance after the vehicle is
exposed to water under normal vehicle operation, such as in a car wash
or while driving through a pool of standing water. As in GTR No. 20,
the proposed test procedures specify the use of freshwater. The
proposed physical test requirements comprised of two tests. The
proposed washing test was similar to that in GTR No. 20, with the
addition of exposing the vehicle underbody to the water stream to make
the test more representative of vehicle washing. The proposed driving
through standing water test was also similar to that in GTR No. 20, but
with the maximum test duration reduced from 10 minutes to 5 minutes.
Electrical isolation was proposed to be determined at the conclusion of
each test, and once again after 24 hours.
The NPRM did not propose to allow the documentation or isolation
loss warning compliance options from GTR No. 20 for the water exposure
tests. The NPRM requested comment on the proposed test specifications,
including water pressure for the washing test. The NPRM also requested
comment on water salinity levels for the tests as well as potential
test procedures for submersion.
Comments Received
There were a variety of comments on the water exposure
requirements. Some commenters agreed with the proposed test procedures,
while others requested additional compliance options or changes to the
test specifications. For the washing test, Tesla stated support for the
proposed test method and recommended keeping the freshwater
specification from GTR No. 20. Auto Innovators suggested establishing a
maximum test duration and changing the timing of the isolation checks
to 12 hours to reduce the time burden. Auto Innovators said the test
parameters should not include salinity because it is unnecessary and
because a large amount of water will be needed, and the reproducibility
of salinity levels is challenging. Nissan also said that using saline
in the proposed tests would not significantly impact the evaluation and
is unnecessary.
Hyundai requested clarification for the underbody spray distance
and angle for the proposed test procedure to ensure the test is clear
and repeatable. For water pressure, Eaton agreed with adopting IPX5 for
normal driving conditions. NEMA also agreed that IPX5 matches normal
conditions but suggested using IPX7 to address submersion concerns.
Nikola said, ``Increasing the pressure does seem prudent as it will be
the standard practice to use a pressure washer to clean the vehicles,''
and suggested IPX6.
Eaton stated support for the inclusion of the driving through
standing water test. Tesla also agreed with the proposed procedure and
suggested keeping the long rectangular pool for ease of defining
driving and test evaluation methodologies. As with the washing test,
Auto Innovators said there should not be a salinity requirement and
requested changing the timing of the isolation checks to 12 hours.
Prevost and EMA opposed the driving through standing water test for
heavy vehicles. Prevost said, ``Since NHTSA suggests improving vehicle
washing test by adding the underside of the vehicle to the scope of the
test, the driving through standing water tests does not seem to add
value to the safety of the vehicle, as the washing test with the
underbody included will be a harsher requirement than driving through
10cm of water at 20kph . . . Since facilities providing the
infrastructures to perform the driving through standing water test will
be scarce, this test would add significant costs while not improving
vehicle safety.'' EMA likewise stated that the washing test is more
aggressive, test facilities for heavy vehicles do not currently exist,
and NHTSA should remove the redundant and expensive driving through
standing water test for heavy vehicles.
Auto Innovators, Hyundai, Nissan, and NFA requested inclusion of
compliance options from GTR No. 20. Hyundai recommended harmonizing
with GTR No. 20 and UNECE R100, in which the electrical isolation loss
warning system is allowed as a compliance option. Nissan similarly
requested a compliance option to harmonize with the UNECE. Auto
Innovators asked that NHTSA allow a component-level test compliance
option, and transit bus manufacturer NFA specifically requested
component-level water exposure safety tests instead of full vehicle
tests for heavy buses and motor coaches. NFA asserted that spraying the
battery pack directly would constitute a more rigorous test than the
proposed full-vehicle tests and said it is open to component-level
testing at the IPX6 level.
With regard to submersion concerns, commenters generally agreed
that further research is necessary, and some urged NHTSA to commit to a
technical amendment. Auto Innovators said that more analysis is needed
before determining whether additional test requirements should be
implemented and recommended harmonizing with UNECE R100. EDTA
recommended that NHTSA commit to a technical amendment and collaborate
with stakeholders in collecting data to establish a test requirement
addressing real-world flooding scenarios. MEMA, NEMA, and Eaton
provided similar comments. Eaton also stated that rigorous test
standards would enable the United States to maintain a position of
technological leadership and prevent lower-quality imports from
entering the market. NEMA said that testing documentation requirements
should include water ingress and egress risks. Nikola said that
submersion in saline should be compared to the salt spray test in
UL2580. Tesla also recommended additional research on salinity. MEMA,
NEMA, EDTA, and Eaton further recommended adding a leak check
requirement for battery packs at the time of manufacture. MEMA and
Eaton specified that the leak checks should include all sealing
surfaces and be implemented as a documentation requirement; Eaton said
the sealing surfaces between vent valves and the battery housing are
often missed in current leak testing practices.

[[Page 104338]]

Agency Response
After consideration of the comments, the agency believes the
proposed test procedures remains practicable and the requirements
mitigate the risk of short circuit or loss of electrical isolation due
to water ingress under normal operating scenarios such as driving
through standing water on the road or vehicle washing. NHTSA is
adopting the proposed requirements with minor changes, including an
increase of the standing water test maximum duration from 5 minutes to
10 minutes due to recent NHTSA testing. For the vehicle washing test,
the NPRM included a figure from GTR No. 20 to specify the dimensions of
the water nozzle and stated that the ``nozzle specifications are from
IEC 60529 for IPX5 water jet nozzle.'' However, the provided figure
depicted the nozzle dimensions from IEC 60034, wherein one internal
dimension of the nozzle deviates from IEC 60529 by 2 mm. As IEC 60034
is specific to rotating electrical machines, it is more appropriate to
use the nozzle specifications from IEC 60529, which was the standard
referenced in the text of the NPRM. For these reasons, this final rule
contains a corrected figure specifying water nozzle dimensions
consistent with IEC 60529.
The NPRM proposed a maximum test duration of 5 minutes for the
driving through standing water test instead of GTR No. 20's 10 minutes
but also sought comment on the maximum duration. NHTSA conducted the
driving through standing water test in August 2024 using a 30-meter
length water pool with a 15-meter approach ramp on both ends of the
pool.\38\ To accumulate 500 meters of driving through 10 cm of standing
water, the vehicle needed to be driven 17 times through the 30-meter
water pool. Based on the testing, the agency determined that a test
duration of 5 minutes may not be sufficient when the test is conducted
using a short water pool. Traversing the entry and exit ramps and
turning around between each pass of the water pool adds to the total
time necessary to complete the test. NHTSA estimates that 7.5 minutes
is sufficient for a water pool length of 30 meters. More time would be
needed to complete the test using water pools shorter than 30 meters.
The maximum test duration time for conducting the driving through
standing water test is 10 minutes in GTR No. 20, which NHTSA agrees is
appropriate. Therefore, this final rule adopts a 10-minute time limit
for the driving through standing water test.
---------------------------------------------------------------------------

\38\ The testing is described in more detail in a separate
document being placed in the docket for this rulemaking.
---------------------------------------------------------------------------

Some comments addressed other parameters of the vehicle washing
test, specifically test time, spray angle, and spray distance. The
maximum test time is not stated because the test procedure specifies
``washing test duration per square meter of the vehicle surface area is
60 to 75 seconds.'' The maximum test time depends on the surface area
of the vehicle, which can be measured in square meters and multiplied
by 75 seconds per square meter to obtain the maximum test duration for
the vehicle. The spray angle provision ensures that all directions are
considered for water resistance and is consistent with the IPX5
standard and GTR No. 20. The test procedure states, ``The vehicle is
sprayed from any direction,'' which means the vehicle must be able to
meet the test requirements regardless of the angles used. With regard
to the spray distance, the proposed requirement said, ``the distance
from the nozzle to the vehicle surface is 3.0 to 3.2 meters [and] may
be reduced, if necessary, to ensure the surface is wet when spraying
upwards.'' The test procedure includes some adjustment to the nozzle
distance because the water stream may not be capable of hitting a
vehicle's lower side and bottom (underbody) unless the nozzle is
pointed upwards and positioned closer than 3.0 to 3.2 meters from these
vehicle surface areas. These provisions are consistent with GTR No. 20.
Further, NHTSA believes the proposed testing parameters provide
sufficient specification and flexibility for a repeatable test, thus,
the agency is adopting the proposed specification.
Regarding the time interval between isolation measurements, Auto
Innovators did not provide any supporting data for the request to
reduce the minimum wait time to 12 hours. The isolation measurements
are conducted immediately after water exposure and after a minimum of
24 hours, which is identical to the GTR No. 20 and ECE R.100
specifications. The agency believes that the 24-hour wait time is
appropriate and consistent with observed electric vehicle fires
initiating a day or longer after water exposure/submersion.\39\ In the
absence of information demonstrating that reducing the time interval
between isolation measurements would not significantly alter the test
results, the agency is adopting the requirements as proposed.
---------------------------------------------------------------------------

\39\ Overview of NHTSA EV Safety Activities, SAE Government
Industry Meeting, January 2023, <a href="https://www.nhtsa.gov/sites/nhtsa.gov/files/2023-03/15874-NHTSA%20SAE%20GIM%202023_final_032223-tag.pdf">https://www.nhtsa.gov/sites/nhtsa.gov/files/2023-03/15874-NHTSA%20SAE%20GIM%202023_final_032223-tag.pdf</a>.
---------------------------------------------------------------------------

Some commenters supported the addition of a warning option.
Although visual warning indicators triggered from an isolation
monitoring system could help mitigate safety concerns, NHTSA believes
that this approach is not sufficient to solely mitigate a shock or fire
hazard caused by the effects of water exposure. Consequently, the
agency is not adopting the loss of isolation warning compliance option
because warning signals alone are not sufficient for addressing loss of
electrical isolation concerns.
Some commenters also requested component-level testing,
particularly for heavy vehicles. The agency believes that component-
level testing is not as representative of actual conditions as full-
vehicle testing. Furthermore, the vehicle washing test does not pose an
undue burden.
The agency also disagrees with EMA and Prevost's requests that
heavy vehicles be excluded from the driving through standing water
test. In support of their position, the two commenters said that test
facilities do not accommodate heavy vehicles, it would be very
expensive to conduct the test, and the test is redundant. The agency
notes that FMVSSs establish minimum safety requirements and the FMVSS
test procedures establish how the agency would verify compliance. The
Safety Act requires manufacturers to ensure their vehicles comply with
all applicable FMVSSs and to certify compliance of their vehicles with
all applicable FMVSSs. The Safety Act specifies that manufacturers may
not certify compliance if, in exercising reasonable care, the
manufacturer has reason to know the certificate is false or misleading.
A manufacturer may use component-level tests to certify its vehicles if
they exercise reasonable care in doing so. Additionally, while NHTSA
agrees that the driving through standing water test may not be as
stringent as vehicle washing for certain heavy vehicle configurations
with greater ground clearance and/or with the REESS located higher on
the vehicle (e.g., on the roof), vehicle configuration is not
prescribed by the FMVSS and is left to the discretion of the
manufacturer. Both water exposure tests represent reasonable scenarios
for normal vehicle operations and establish minimum levels of safety
for water exposure of electric vehicles. With the flexibilities
afforded to manufacturers to certify compliance, NHTSA disagrees that
the cost burden may be excessive for heavy vehicles. Some vehicle
manufacturers suggested use of the IPX6

[[Page 104339]]

or IPX7 standard instead of IPX5. NHTSA agrees that other standards
such as IPX6 or IPX7 may be appropriate for evaluating the water
resistance of electric vehicles. However, the corresponding IPX6 or
IPX7 test procedures were not proposed in the NPRM and are out of scope
for this final rule. While the final rule adopts the proposed
requirements corresponding to IPX5, manufacturers are not prohibited
from additional test methods beyond the FMVSS specifications and may
choose to use the IPX6 or IPX7 standard to evaluate the water
resistance of their vehicles.
The commenters agreed that saline should not be specified for the
test procedures because it would not significantly affect the results
and the salinity level would be difficult to maintain. The commenters
also observed that the test procedures of using fresh water would
harmonize with international standards. At this time, the agency agrees
that generally, water exposure under normal vehicle operation occurs
with freshwater; thus, keeping the freshwater specification is
appropriate for these tests.
With regard to the battery leak check requirements suggested by
some commenters, such requirements were not proposed in the NPRM and
are also out of scope for this final rule. Typical leak check
procedures require access via one of the vent valves; a requirement to
check all sealing surfaces would necessitate a different test method
that does not use an opening in the pack. Additionally, research on
flood-damaged vehicles has shown that water ingress occurs for a
variety of reasons and does not necessarily lead to catastrophic
failure.\40\
---------------------------------------------------------------------------

\40\ A Teardown Study of Flood Damaged Electric Vehicles--EV
Battery Safety, Part 2, SAE Government Industry Meeting, January
2024, <a href="https://www.nhtsa.gov/document/teardown-study-flood-damaged-electric-vehicles-ev-battery-safety-part-2">https://www.nhtsa.gov/document/teardown-study-flood-damaged-electric-vehicles-ev-battery-safety-part-2</a>.
---------------------------------------------------------------------------

NHTSA recognizes that further research is needed on the field
incidences of electric vehicle fires following water exposure,
particularly saltwater exposure, in order to establish additional
requirements. NHTSA is taking the first step by adopting the proposed
water exposure requirements for normal vehicle operations and continues
to research salinity, immersion, and test procedures to support the
development of future safety requirements and inform potential updates
to the FMVSS.

h. Miscellaneous GTR No. 20 Provisions Not Proposed

The NPRM did not propose to require some provisions from GTR No. 20
for vibration, thermal shock and cycling, fire resistance, and low
state of charge (SOC) of the REESS during normal vehicle operations.
The NPRM requested comment on these exclusions.

j. Vibration and Thermal Shock and Cycling

NPRM Discussion
As stated in the NPRM, GTR No. 20 contains a vibration requirement
and test procedure that applies a generic vertical vibration profile to
the tested vehicle. NHTSA believes that this test is not representative
of real-world conditions. In addition, vehicle manufacturers routinely
perform vibration testing to ensure customer satisfaction and
reliability. At the component level, electric vehicle batteries are
currently subject to vibration test requirements for transportation
under the United States Hazardous Materials Regulations (HMR), along
all three orthogonal axes and for frequencies up to 200 Hz. With these
current tests, NHTSA does not believe that the GTR No. 20 vibration
test would address an additional safety need.
Similarly, at the component level, REESSs are already subject to
thermal cycling test requirements for transportation under the HMR. 49
CFR 173.185 requires lithium-ion cells and batteries to comply with the
test requirements in UN 38.3, including Test T2: Thermal test, which is
the basis of the GTR No. 20 thermal shock and cycling test and includes
a larger temperature range. NHTSA believes that incorporating the GTR
No. 20 test would not address an additional safety need.
Comments Received
Comments from Auto Innovators and HATCI stated agreement with the
agency's rationale and exclusion of these requirements. Regarding the
vibration and thermal shock and cycling requirements of GTR No. 20,
HATCI agreed with NHTSA's rationale for not including the tests given
the more stringent U.S. regulations. Auto Innovators also agreed that
introduction of new vibration profiles is unnecessary, as the test may
not be representative of real-world conditions and industry uses other
means to assess durability. For thermal shock and cycling, Auto
Innovators said the test requirements in UN 38.3 T2 are sufficient.
However, Nikola disagreed with the agency's decision not to add the
thermal shock and cycling test. Nikola said that the HMR requirements
are insufficient because UN 38.3 does not require testing of the
assembled battery pack, and that relying on the shipping requirements
for the cells or modules is a low bar to set for safety.
Agency Response
After reviewing the comments, the agency is not adopting additional
requirements for vibration and thermal shock and cycling. Commenters
agreed with the agency's rationale for excluding the vibration test
requirements. Nikola said the thermal shock and cycling test
requirements in GTR No. 20 should be included because testing of cells
or modules is not equivalent to testing of the full battery pack; UN
38.3 does not require pack level testing if the cells and modules were
tested. However, Nikola did not provide any data demonstrating that the
existing requirements may be insufficient. For the final rule, the
agency does not believe there is a safety need for additional thermal
shock and cycling test requirements. In the absence of new supporting
information, NHTSA maintains that UN 38.3 and the HMR appropriately
address resistance to thermal shock and cycling for lithium cells and
batteries.
2. Fire Resistance
NPRM Discussion
The GTR No. 20 fire resistance requirement applies to REESSs with
flammable electrolyte installed in a vehicle at a height less than 1.5
m above the ground and is based on a UN Regulation for liquid fueled
vehicles with plastic tanks. During the test, the REESS is exposed to a
flame directly for 70 seconds and indirectly for 60 seconds. As stated
in the NPRM, vehicle testing by Transport Canada indicated that the
short duration of the external fire test would not result in explosion.
Consequently, during Phase 1 of the GTR No. 20 discussions, the United
States and Canada noted that the short duration component level test
would not address a safety need and recommended removing it from GTR
No. 20.
Comments Received
As with the vibration and thermal shock and cycling tests, HATCI
expressed agreement with NHTSA's decision not to include the fire
resistance test. Auto Innovators also agreed, stating that a test
duration of under 10 minutes is insufficient to induce significant
internal heating. Again, Nikola disagreed, stating that the vehicle
testing by Transport Canada

[[Page 104340]]

does not support the exclusion because industry designed its vehicles
to be able to withstand the test. As a result, Nikola said excluding
the requirement from the FMVSS could lead to less safe EV designs.
Agency Response
After reviewing the comments, the agency is not adopting the short
duration fire resistance test. One commenter said that manufacturers
design for the test and the exclusion could reduce safety. However, the
agency does not believe that excluding the test requirement will lead
manufacturers to redesign U.S. vehicles or REESSs in a manner that
reduces the resistance to flame from below. The comments did not
provide any new and supporting data on fire exposure or design. In the
absence of further information demonstrating a safety need, the agency
is not adopting the fire resistance test requirement at this time.
3. Low State of Charge (SOC) Telltale
NPRM Discussion
GTR No. 20 requires a telltale to the driver in the event of low
REESS SOC. The NPRM did not propose the low SOC telltale because NHTSA
believes this requirement is unnecessary because there is no
corresponding low fuel warning requirement for conventional internal
combustion engine vehicles. The NPRM requested comment on whether NHTSA
should adopt the GTR No. 20's low SOC telltale requirement, and if yes,
what the telltale should look like.
Comments Received
All of the comments on the low SOC telltale requirement agreed with
NHTSA's proposal not to require a low SOC telltale. Nissan and Auto
Innovators both stated that regulation is unnecessary because
manufacturers already provide SOC information. HATCI likewise agreed
with the stated rationale. Nikola also agreed with the exclusion, as
``a requirement for low SOC would require standardizing when the light
was to come on [and] it should be left up to the OEM.''
Agency Response
After reviewing the comments, the agency is not adding a low SOC
telltale requirement. The agency believes that all electric-powered
vehicles already provide low SOC telltales due to consumer demand.
Regulation is unnecessary and excluding the low SOC telltale
requirement is appropriate and consistent with not having a low fuel
warning regulatory requirement for conventional internal combustion
engine vehicles.

j. Low-Speed Vehicles

NPRM Discussion
The NPRM requested comments on applying aspects of FMVSS No. 305a
to electric low-speed vehicles that travel under 40 km/h (25 mph) (as
defined in 49 CFR 571.3).\41\ particularly for normal vehicle
operations and safe operation of the REESS. The agency requested
comment on the possible applicability of FMVSS No. 305a to low-speed
vehicles and its relevant safety needs, including any supporting
research on low-speed vehicles.
---------------------------------------------------------------------------

\41\ See FMVSS No. 500, ``Low speed vehicles,'' 49 CFR 500.
---------------------------------------------------------------------------

Comments Received
A few commenters addressed the inclusion of low-speed electric
vehicles (LSEVs). NTSB said that LSEVs should be included, as the risks
and potential hazards are well established and because NHTSA's proposed
operational requirements involve appropriate safety planning and no
performance measure or tests, and cited the collision of an autonomous
electric shuttle that occurred in 2017. On the other hand, MEMA said
the standard should not apply to LSEVs. Honeywell stated support
specifically for application of the thermal event warning requirement,
because low-speed vehicles often use the same battery cell types as
cars and are likewise at risk for thermal events.
Agency Response
After reviewing the comments, the agency is not adopting additional
requirements for LSEVs at this time. In general, low-speed vehicles
such as golf carts are not subject to the same requirements as higher-
speed motor vehicles. LSEVs are subject to FMVSS No. 500, ``Low-speed
vehicles,'' which specifies required safety requirements for low-speed
vehicles. While thermal events and other hazards are a concern for any
rechargeable battery system, LSEVs generally have smaller batteries
than higher-speed motor vehicles and are not subject to the same use
conditions. The comments did not provide any supporting research on
low-speed vehicles demonstrating a safety need for additional
requirements. The autonomous shuttle crash cited by NTSB occurred at a
very low speed and did not exhibit any safety hazards from the REESS.
NHTSA will continue to assess electric vehicle safety and the need to
establish additional requirements for LSEVs in the future when
additional data is available.

j. Emergency Response Information

Proposed Requirements
The NPRM proposed to require manufacturers to submit standardized
emergency response information for each vehicle model and model year to
NHTSA's website for public access. The emergency response information
would include the rescue sheet and the emergency response guide (ERG).
The rescue sheets must follow the layout and format in ISO-17840-
1:2022I (for vehicles with a GVWR less than or equal to 4,536 kg
(10,000 lb)) and the format in ISO-17840-2:2019(E) (for vehicles with a
GVWR greater than 4,536 kg (10,000 lb)). The ERGs must follow the
template layout and format of ISO-17840-3:2019(E) and provide in-depth
information linked and aligned to the corresponding rescue sheet to
support the quick and safe action of emergency responders. The NPRM
proposed that electronic versions of the rescue sheets and ERGs for all
vehicles to which FMVSS No. 305a applies must be submitted prior to
certification of the vehicle.
Comments Received
Many commenters expressed support for NHTSA's collection of
standardized emergency response information. Consumer Reports, DTNA,
EMA, Lucid, Nikola, Tesla, Volkswagen, ZETA, CAS, and EV Rescue App
were among the commenters that stated agreement with the proposed
requirements. Firefighter and ISO project leader Kurt Vollmacher also
expressed support for the use of ISO 17840 and for the establishment of
a central database. Some commenters asked for clarification of the
requirements, suggested additional provisions, or requested
modification to the submission timeline.
NTSB expressed strong support for all aspects of the proposed ERG
and rescue sheet submission requirements, stating that NHTSA's proposal
is a better approach than incorporating the information as part of the
New Car Assessment Program, as NTSB originally recommended. NTSB agreed
with hosting the standardized documents on a NHTSA website and
suggested that NHTSA work with NFPA to redirect users to the new source
of information. NTSB also stated that it is important to include the
legacy information from the NFPA website because responders interact
with vehicles from previous model years. Lucid likewise said NHTSA
should include the ERGs from the NFPA site.
HATCI, Auto Innovators, and NFA expressed general support for the
proposed requirements but requested

[[Page 104341]]

clarification. HATCI said, ``it is unclear the method by which the
Agency plans to have manufacturers submit these documents and how the
Agency intends to process the submissions,'' and inquired whether
NHTSA's proposal intends to replace the NFPA's housing of information
or if manufacturers will need to submit the ERGs to multiple locations.
Auto Innovators likewise said NHTSA should provide clear information
and guidance for uploading the information to the NHTSA website to
ensure timeliness and accuracy, and should ``clarify its interpretation
of ISO 17840 as the current standard on which all rescue sheets and
ERGs should be based.'' NFA asked ``whether it would be permissible to
consolidate the Rescue Sheet and ERG into a single document.''
With regard to the submission timeline, Auto Innovators requested
``that NHTSA establish a process to ensure that ERGs are made available
starting on the date when the subject vehicle is first introduced for
sale in the United States . . . to protect final design information.''
Volkswagen also requested submission just prior to market introduction,
to allow the manufacturer to reserve its final design pictures or plans
for press and social media release. Volkswagen said there would be no
added risk to this timeline because the vehicle would not be available
for sale or on public roads during this time.
Other suggestions from Auto Innovators were for NHTSA to establish
a website with a distinct URL for ease of access, increase first
responder awareness of the new resource through safety marketing, and
consider partnerships for mobile and desktop applications as seen with
Euro NCAP. Lucid suggested an additional requirement for ERGs to
provide high-voltage warnings and identify proper personal protective
equipment for dealing with high-voltage systems. Nikola said NHTSA
should have the standardized ERGs submitted to NFPA, because the first
responder industry knows to go to the NFPA website for information.
Agency Response
After reviewing the comments, the agency is adopting the proposed
emergency response information requirements in part 561. Comments were
largely in favor of the requirements, including standardization and
submission of the documentation. The required documents must be
vehicle-specific and conform to the ISO-17840's layout and format,
which are incorporated by reference in part 561. Adoption of the
existing standardization means that vehicle manufacturers, as well as
first and second responders, are already accustomed to the content and
formatting of the ERGs and rescue sheets, and that the documents are
consistent. The standardized color-coded sections in a specific order
will help first and second responders quickly identify pertinent
vehicle-specific rescue information. Both the ERG and the rescue sheet
are required, as the ERG provides relevant, in-depth information for a
variety of potential incidents, while the rescue sheet is a shorter,
simpler document for quick reference. The headings/contents of the
rescue sheet and the ERG information from ISO are aligned with each
other, i.e., the ERG information works as an extension of the related
rescue sheet. Consequently, due to the varying emergent situations that
could occur, the ERG and rescue sheet should be provided as separate
documents for the relevant safety need, consistency, and ease of access
without confusion.
With regard to document submission and processing, the manufacturer
will upload the emergency response documentation to the designated
NHTSA website, <a href="https://www.NHTSA.gov/ERG">https://www.NHTSA.gov/ERG</a>.\42\ The files will be
publicly available and searchable by vehicle make, model, and model
year, as provided at the time of upload. The documents should be
submitted as PDF files per the guidelines provided on the website.
NHTSA will not modify the contents of the documents submitted by the
manufacturer. The manufacturer is responsible for submitting the
correct ERG and rescue sheet files for each vehicle model and model
year, including any subsequent updates or corrections that are needed.
Secure user login will be provided for manufacturers to upload and
manage documents. The ERGs and rescue sheets will be available to the
public for viewing and to download without a login.
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\42\ The website is expected to go online in February 2025.
Instructions for manufacturers regarding login credentials and file
uploads will be provided on the website at a later date.
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Some commenters requested later submission of the emergency
response documents to protect final design information prior to market
introduction without affecting safety. NHTSA agrees that a later
submission date than the proposed certification date is appropriate and
has revised the timeline accordingly. This final rule requires
manufacturers to submit the emergency response guides and rescue sheets
prior to first sale or lease of the subject vehicle model in the United
States.
Commenters requested clarification on the legacy ERGs that are
currently housed in the NFPA website \43\ and whether manufacturers
should be submitting ERGs to multiple locations. NHTSA is coordinating
with NFPA on ERGs currently housed with NFPA to migrate these legacy
documents to the NHTSA specific website. Manufacturers will only need
to submit the ERGs and rescue sheets to the NHTSA specified website
prior to first vehicle sale or lease on the specified compliance date.
NHTSA will socialize the location of the NHTSA website to first and
second responders.
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\43\ <a href="https://www.nfpa.org/education-and-research/emergency-response/emergency-response-guides#aq=%40culture%3D%22en%22&cq=%40taglistingpage%3D%3D">https://www.nfpa.org/education-and-research/emergency-response/emergency-response-guides#aq=%40culture%3D%22en%22&cq=%40taglistingpage%3D%3D</a>(%22EV%20Gu
ides%22)%20%20&numberOfResults=12&sortCriteria=%40title%20ascending.
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k. Documentation Requirements

NPRM Discussion
The NPRM requested comments on whether the proposed emergency
response information requirements would be better placed in a general
agency regulation than in FMVSS No. 305a, given that the documentation
specifications are more akin to a disclosure requirement (disclosing
information to NHTSA and the public) than a performance test or a
consumer safety information requirement. The NPRM also sought comments
on whether the proposed risk mitigation documentation requirements
would be better placed in a general agency regulation. The mechanisms
for enforcing a failure to meet a documentation requirement could
differ depending on whether the requirement is in an FMVSS or not.
Comments Received
Comments on the documentation provisions were mixed. For the
emergency response information, NTSB said that the emergency responder
information requirements are straightforward enough to be included in
this proposed rulemaking and should not be delayed for a separate
regulation. MEMA stated that it agrees with NHTSA's proposed
documentation provisions, with due regard for the protection of
confidential business information that may be contained therein. Auto
Innovators requested that NHTSA consider initiating rulemaking to add a
Class Determination to 49 CFR part 512 for the technical documentation
submissions to be presumptively confidential.
Most manufacturers and manufacturer associations that commented on
this

[[Page 104342]]

topic argued that the documentation should not be included in FMVSS No.
305a. Auto Innovators asserted that the documentation requirements are
not objective standards and that reporting requirements should not be
subject to the same recall and remedy obligations for FMVSS compliance.
They reasoned that documentation does not directly affect safety and
may be subject to change over time. Comments from DTNA, HATCI, EMA,
NFA, and Nikola were similar. DTNA said the documentation requirements
should be moved because the documentation is not associated with the
vehicle meeting the performance requirements or information necessary
to carry out the test procedure. HATCI said, ``Minor or subjective, yet
remediable, inquiries or revision requests and other inconsequential
errors could be inordinately difficult to resolve within the framework
of an FMVSS.''
Agency Response
After reviewing the comments, the agency agrees that the
documentation requirements are better suited to a separate regulation
than inclusion in FMVSS No. 305a. NHTSA regulates motor vehicle safety
under many grants of authority. For example, one such authority is that
NHTSA is authorized by the Vehicle Safety Act to issue FMVSS; a typical
FMVSS specifies minimum performance requirements and may also include
provisions requiring manufacturers to provide consumers safety
information on properly using a safety system or item of equipment.
Another is that the Vehicle Safety Act authorizes NHTSA to require
manufacturers to retain certain records and/or make information
available to NHTSA. Section 30166 of the Vehicle Safety Act provides
NHTSA the ability to request and inspect manufacturer records that are
necessary to enforce the prescribed regulations. NHTSA is also
authorized by delegation to issue regulations to carry out the agency's
duties of ensuring vehicle safety.\44\ Documentation requirements would
be authorized under these authorities.
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\44\ 49 U.S.C. 322(a). This provision states that the Secretary
of Transportation may prescribe regulations to carry out the duties
and powers of the Secretary. The authority to implement the Vehicle
Safety Act has been delegated to NHTSA.
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NHTSA is also mindful that the mechanisms for enforcing a failure
to meet a documentation requirement could differ depending on whether
the requirement is in an FMVSS or not. Section 30118 of the Vehicle
Safety Act (49 U.S.C. 30118) provides that whenever the Secretary of
Transportation (NHTSA by delegation) determines that a vehicle does not
comply with an FMVSS, NHTSA (by delegation) must require the vehicle's
manufacturer to notify the owners, purchasers and dealers of the
vehicle or equipment of the noncompliance and remedy the noncompliance.
An exception to the recall requirement in section 30120(h) authorizes
NHTSA to exempt noncompliances from recall provisions based on a
demonstration that the noncompliance is inconsequential to safety. In
the case of a violation of a disclosure requirement in a regulation
other than an FMVSS, the manufacturer could be subject to injunctive
remedies and/or civil penalties,\45\ but would not be subject to a
recall notification and remedy provision described above.
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\45\ See, e.g., 49 U.S.C. 30165.
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After consideration of the nature of the documentation
specifications and corresponding enforcement mechanisms, this final
rule establishes the technical documentation and emergency response
documentation requirements in part 561, without additional delay. As
proposed, submission of the emergency response information is required
for all subject vehicles, while submission of the other documentation
specified in part 561 is upon request. Requested documentation may be
submitted as Confidential Business Information (CBI) under 49 CFR part
512. NHTSA will follow 49 CFR part 512 confidential submissions
procedures.
Aligned with NHTSA's average record keeping requirements for
regulations, the corresponding documentation requirements are required
to be retained for five years.\46\
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\46\ For example, prior to the final rule published on August
16, 2024 (89 FR 66629), NHTSA's record retention period, under 49
CFR 576, for motor vehicles, child restraint systems, and tires
concerning malfunctions that may be related to motor vehicle safety
under the Safety Act was 5 years.
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l. Compliance Dates

Proposed Requirements
The NPRM proposed a compliance date of two years after the
publication of the final rule for the proposed requirements other than
the emergency response information. The NPRM proposed a compliance date
of one year after the final rule's publication for the proposed
emergency response information submission to NHTSA to assist first and
second responders. The NPRM further proposed that small-volume
manufacturers, final-stage manufacturers, and alterers would be
provided an additional year to comply with each of the requirements.
Optional early compliance would be permitted.
Comments Received
MEMA agreed with the proposed compliance dates, while several other
commenters requested additional time for the technical requirements.
HATCI agreed with the compliance dates for the emergency response
information but requested an additional year for the other requirements
because some proposed provisions deviate from GTR No. 20 and heavy
vehicle manufacturers will be newly subject to electric system
integrity requirements. Auto Innovators also agreed with the one-year
lead time for manufacturers to submit the required emergency response
guides and rescue sheets but requested an additional two years beyond
the proposed compliance date for the other requirements. In other
words, they requested a lead time of 4 years, because substantive
design changes might be required. They supported allowing an additional
year for small-volume manufacturers, final-stage manufacturers, and
alterers. EMA requested a 5-year lead time for heavy vehicles because
heavy duty vehicle manufacturers will need to perform validation
testing and make the appropriate design and production changes.
Bugatti requested a longer lead time for small-volume manufacturers
because ``the proposed lead periods do not allow sufficient time for
the necessary assessments and validation to be conducted properly for
small volume manufacturers and including final-stage manufacturers.''
Bugatti stated that the dates should be aligned with FMVSS No. 127,
``Automatic Emergency Braking Systems for Light Vehicles,'' which has
compliance dates of September 2029 and September 2030, so that multiple
high impact regulations start simultaneously. For FMVSS No. 305a, these
dates would result in lead times of approximately 5 years for large
volume manufacturers and 6 years for small volume and final-stage
manufacturers.
Agency Response
After reviewing the comments, the agency is adopting the proposed
compliance date for the emergency response information requirements in
part 561. The compliance date is one year after publication of this
final rule for all applicable vehicles. NHTSA believes the 1-year
compliance date for this proposed requirement is long enough for
manufacturers to provide the information to NHTSA in the required
format. They are already providing the information voluntarily to the
NFPA. In

[[Page 104343]]

the interest of public safety, the agency would like to provide the
information on NHTSA's website as soon as possible. If manufacturers
provide the information in a year, NHTSA can begin the process of
posting the information shortly thereafter. Commenters agreed with the
proposed compliance date for submission of the emergency response
information to support first and second responders.
In response to the concern raised about proprietary information of
new vehicle designs being made public before first sale or lease, the
final rule submission timeline requires manufacturers to submit the
emergency response guides and rescue sheets prior to first sale or
lease of the subject vehicle model in the United States. In the first
year that compliance with this requirement becomes mandatory, the
compliance date may not coincide with the first sale or lease of a
vehicle model for that year. In this case, the first sale or lease of
the vehicle model on or after the mandatory compliance date is the time
before which the emergency response information for the vehicle model
must be submitted.
This final rule modifies the proposed compliance date of two years
after publication of the final rule for light vehicle requirements,
other than the emergency response information, such that the compliance
date starts on the first September 1 that is at least 2 years after the
final rule publication date to correspond to when a vehicle model year
typically begins, instead of the originally proposed two years after
the final rule publication.
HATCI requested an additional year and Auto Innovators requested an
additional two years to meet the proposed requirements for light
vehicles because some proposed provisions deviated from GTR No. 20.
While the final rule generally adopts the proposed requirements,
changes to the final rule largely align with GTR No. 20, such as the
adoption of documentation for the thermal event warning requirement
instead of a corresponding testing procedure and clarification of the
definition of SOC. These final rule changes reduce the burden for
additional lead time for compliance because of widespread voluntary
compliance with GTR No. 20. Therefore, we believe a compliance date of
the first September 1 that is at least 2 years after the publication of
this final rule is sufficient for manufacturers of light vehicles to
ensure compliance with the final rule.
On the other hand, the agency is extending the compliance date for
heavy vehicle requirements by an additional year from the originally
proposed one year after the publication of the final rule. NHTSA
recognizes that heavy vehicles are not subject to the current FMVSS No.
305, and additional lead time is needed because design changes may be
needed for heavy vehicles. As noted earlier, the changes made in the
final rule better align with GTR No. 20 requirements. However, the
final rule requires vehicle level testing that is optional in GTR No.
20 and requires overcurrent protection of the REESS for heavy vehicles
that is not required in GTR No. 20. NHTSA acknowledges that heavy
vehicle manufacturers may need time to assess fleet performance, review
their risk management procedures, and document their mitigation
strategies since they are newly subject to electric system integrity
requirements. The agency believes a compliance date of the first
September 1 that is at least 3 years after publication of the final
rule is sufficient for applicable heavy vehicles to comply with FMVSS
No. 305a.
Under 49 U.S.C. 30111(d), a standard may not become effective
before the 180th day after the standard is prescribed or later than one
year after it is prescribed, unless NHTSA finds, for good cause shown,
that a different effective date is in the public interest and publishes
a reason for the finding. A phased-in compliance period of two to four
years that also aligns with the normal vehicle design cycle (model
year) is in the public interest because most vehicles will require
upgrades of hardware or software to meet the requirements of this final
rule. To require compliance with this standard outside of the normal
development cycle would significantly increase the cost of the rule
because vehicles cannot easily be made compliant with the requirements
of this final rule outside of the normal vehicle design cycle.
Note that as discussed in the Regulatory Flexibility Act section of
this document, NHTSA is giving small-volume manufacturers, final-stage
manufacturers, and alterers an additional year to comply.\47\ Optional
early compliance is permitted. Additionally, in the interest of public
safety, the effective date of this final rule is 60 days after its
publication to establish the new requirements in the Code of Federal
Regulations and to allow for optional early compliance.
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\47\ 49 CFR 571.8(b).
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V. Response to Comments on

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