`[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 [www.gpo.gov]
[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 http://www.regulations.gov, 
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 https://www.transportation.gov/individuals/privacy/privacy-act-system-records-notices.
    Docket: For access to the docket to read background documents or 
comments received, go to https://www.regulations.gov 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: [email protected]; Facsimile: (202) 493-
2739. For legal issues, you may contact Ms. K. Helena Sung, Office of 
Chief Counsel; Telephone: (202) 366-2992; Email: [email protected]; 
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, https://unece.org/fileadmin/DAM/trans/main/wp29/wp29wgs/wp29gen/wp29registry/ECE-TRANS-180a20e.pdf.
    \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)

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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, https://www.ntsb.gov/safety/safety-studies/Documents/SR2001.pdf.
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    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. 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 authorized by 
delegation to issue regulations to carry out the agency's duties of 
ensuring vehicle safety.\8\
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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.

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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:

 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
 Management of REESS emitted gases
 Water exposure during vehicle washing and driving through 10-
centimeter (cm) deep water on roadway
 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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 Resistance to short duration external gasoline pool fire *
 Vibration environment during normal vehicle operations *

    Warning systems for REESS safe operation in case of:

 Low energy content in REESS *
 REESS control operational failure
 Thermal runaway propagation due to single cell short circuit 
in REESS
 Thermal event in REESS
 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:
     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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     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.
     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).
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    \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.
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    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\ https://www.nhtsa.gov/battery-safety-initiative.
---------------------------------------------------------------------------

    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, https://rosap.ntl.bts.gov/view/dot/55584.
---------------------------------------------------------------------------

    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, https://www.nhtsa.gov/sites/nhtsa.gov/files/documents/12848-lithiumionsafetyhybrids_101217-v3-tag.pdf.
---------------------------------------------------------------------------

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,'' https://unece.org/sites/default/files/2024-01/R0100r3e.pdf.
---------------------------------------------------------------------------

    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,'' https://unece.org/sites/default/files/2024-07/R094r4e.pdf.
---------------------------------------------------------------------------

    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 https://unece.org/sites/default/files/2024-01/R0100r3e.pdf.
---------------------------------------------------------------------------

    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, https://rosap.ntl.bts.gov/view/dot/42551.
    \25\ Test reports and laboratory test procedures are available 
in the docket NHTSA-2021-0029. https://www.regulations.gov/docket/NHTSA-2021-0029/document, 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, https://rosap.ntl.bts.gov/view/dot/40791.
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \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. https://nrd-static.nhtsa.dot.gov/reports/vehdb/v10000/v14200/v14218R001.pdf.
    \28\ Electric Vehicle GTR No. 20 Test Development, Validation, 
and Assessment, DOT HS 812 092, April 2021, https://rosap.ntl.bts.gov/view/dot/55584.
---------------------------------------------------------------------------

    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. https://rosap.ntl.bts.gov/view/dot/42551.
---------------------------------------------------------------------------

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 (https://www.regulations.gov/docket/NHTSA-2024-0012).
---------------------------------------------------------------------------

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\ https://www.nhtsa.gov/battery-safety-initiative.
---------------------------------------------------------------------------

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. https://www.osti.gov/servlets/purl/1605985.
---------------------------------------------------------------------------

    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. https://webstore.ansi.org/industry/automotive/electric/safety/functional-safety-iso-26262?psafe_param=1&gad_source=1&gclid=Cj0KCQjw99e4BhDiARIsAISE7P_bipjmLqkehMPUorfq0x2h6lAVWmd0GSbo7Z7qRtwAI-Rfd40YBMUaAuMuEALw_wcB.
---------------------------------------------------------------------------

    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, https://www.nhtsa.gov/sites/nhtsa.gov/files/2023-03/15874-NHTSA%20SAE%20GIM%202023_final_032223-tag.pdf.
---------------------------------------------------------------------------

    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, https://www.nhtsa.gov/document/teardown-study-flood-damaged-electric-vehicles-ev-battery-safety-part-2.
---------------------------------------------------------------------------

    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, https://www.NHTSA.gov/ERG.\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.
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \43\ https://www.nfpa.org/education-and-research/emergency-response/emergency-response-guides#aq=%40culture%3D%22en%22&cq=%40taglistingpage%3D%3D(%22EV%20Gu
ides%22)%20%20&numberOfResults=12&sortCriteria=%40title%20ascending.
---------------------------------------------------------------------------

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.
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

    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.
---------------------------------------------------------------------------

    \45\ See, e.g., 49 U.S.C. 30165.
---------------------------------------------------------------------------

    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\
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

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.
---------------------------------------------------------------------------

    \47\ 49 CFR 571.8(b).
---------------------------------------------------------------------------

V. Response to Comments on Issues Not Discussed in the NPRM

a. Future Battery Chemistries

Comments Received
    MEMA suggested limiting the application of FMVSS No. 305a to 
lithium battery vehicles, to better align with GTR No. 20 and avoid 
misconceptions regarding other future battery chemistries. Using 
Environmental Protection Agency (EPA)'s 40 CFR 86.1840-01 ``Special 
test procedures'' as an example, Rivian suggested that NHTSA 
incorporate a similar provision into the regulatory text to address new 
chemistries, allowing manufacturers to submit alternative test 
procedures for NHTSA's review and advanced approval.
Agency Response
    The agency believes that limiting the scope of FMVSS No. 305a to 
only lithium-ion batteries would not be beneficial to safety. There are 
safety risks with any type of propulsion system and any battery 
chemistry. While the FMVSS requirements are based on the current state 
of technology, they are intentionally chemistry neutral to allow for 
future developments. This neutral approach would not limit adoption of 
future battery chemistries and not be design restrictive. The emissions 
requirements cited by Rivian include additional provisions because 
vehicle manufacturers are required to obtain a certificate of 
conformity from the EPA. NHTSA's authority and regulation requirements 
are different from EPA's. NHTSA is authorized to issue FMVSSs that set 
performance requirements for new motor vehicles and items of motor 
vehicle equipment (see 49 U.S.C. Chapter 301). NHTSA does not provide 
approval of motor vehicles or motor vehicle equipment, and NHTSA does 
not determine compliance of a vehicle or item of motor vehicle 
equipment outside the context of an actual enforcement proceeding. 
Instead, manufacturers are required to self-certify that their products 
conform to all applicable safety standards that are in effect on the 
date of manufacture. FMVSS No. 305a does not specify or prohibit 
certain battery chemistries. Overall, NHTSA will continue to monitor 
the state of REESS technology and associated safety risks, and FMVSS 
requirements may be added or modified over time as REESS technology 
evolves.

b. Marking and Labeling

Comments Received
    The Center for Auto Safety suggested NHTSA to establish and require

[[Page 104344]]

distinctive marking in REESS-equipped vehicles to identify REESS-
associated electrical shock hazards, electrical isolation points and 
mechanisms, and related design features by means of standardized, 
permanently affixed labels for reference by emergency personnel and 
consumers. Similarly, Consumer Reports suggested adding requirements 
for hazard warning labels aimed at consumers and maintenance 
technicians.
Agency Response
    The NPRM did not propose additional requirements for specific, 
standardized markings or labeling of electric vehicles, and they are 
not in scope for this final rule. FMVSS No. 305, S5.4.1.1 currently 
requires high voltage cables to have an orange-colored outer covering 
and electric energy storage devices and electrical protection barriers 
to have a specific black and yellow high voltage marking. This final 
rule adopts these same high voltage identification requirements into 
FMVSS No. 305a, S6.1.1. In general, major maintenance and repair of 
electric vehicles is conducted by trained personnel at a manufacturer 
approved dealership; consumers are advised not to attempt modification 
or repair of high voltage systems. Emergency response personnel use 
vehicle documentation to help locate specific components, avoid 
electric shock hazards, and handle the vehicles safely. This final rule 
requires manufacturers to provide standardized ERGs and rescue sheets 
to NHTSA to create a centralized location for public access. In 
addition, some states already require specific license plates or other 
markings on the exterior of alternative fuel vehicles. NHTSA will 
continue to evaluate the type, location, and effectiveness of exterior 
markings that would further aid first and second responders and support 
general emergency mitigation.

c. Test Laboratories

Comment Received
    A2LA suggested adopting conformity assessment activities such as 
requiring manufacturers to use ISO/IEC 17025 accredited testing 
laboratories.
Agency Response
    As discussed above, NHTSA does not specify manufacturer development 
methods or test facility certifications. NHTSA does not provide 
approval of motor vehicles or motor vehicle equipment, and NHTSA does 
not determine compliance of a vehicle or item of motor vehicle 
equipment outside the context of an actual enforcement proceeding. 
Instead, manufacturers are required to self-certify that their products 
conform to all applicable safety standards that are in effect on the 
date of manufacture.

d. Other Electrical Specifications

Comments Received
    EMA suggested adding definitions to S4 for ``Tested-Device,'' 
``Nominal voltage,'' and ``Suitable Lamp.'' EMA also requested changing 
``working voltage'' to ``nominal voltage'' in S7.1.2. For the loss of 
electrical isolation warning in S6.4, EMA suggested adding a 1-minute 
time limit for activation of the visual warning. EMA also requested 
removing the minimum voltage supply for the optional lamp in the 
physical barrier tests, as most vehicles have a standard voltage of 12 
or 24 volts. EMA also said that S7.1 specified the voltmeter internal 
resistance be at least 10 MW and that it should be changed to 10 
M[Omega], and that ``chamber'' should be corrected to ``chamfer'' in 
figure 7b. For high voltage sources excluded from electrical isolation 
requirements, MEMA recommended harmonization with UNECE R100 to clarify 
that the 60VDC threshold also applies to pulsating DC voltages less 
than 60VDC in cases where there is no change in polarity.
Agency Response
    NHTSA appreciates the commenters' review of the regulatory text and 
recommended updates. NHTSA's response to each issue raised is as 
follows:
    1. Definition of Tested-Device: EMA requested allowing component-
level testing and defining ``Tested-Device.' This final rule does not 
use the term ``Tested-Device,'' because all tests are conducted at the 
full vehicle level and there are no component level tests in FMVSS No. 
305a. The April 2024 NPRM used the definition for SOC that is in GTR 
No. 20, which refers to the charge of the ``tested device.'' However, 
in response to comments received, the SOC definition has been revised 
and now refers to the ``REESS'' instead of the ``tested device.''
    2. Definition of Suitable Lamp: S7.3.1 of FMVSS No. 305a describes 
the test procedure for evaluating protection from direct contact with 
high voltage sources. S7.3.1(c) specifies that a ``suitable lamp'' in 
series with a low voltage supply of 40-50 volts may be connected 
between the access probe (IPXXB or IPXXD) and any high voltage live 
parts inside the electrical protection barrier to indicate whether high 
voltage live parts were contacted. EMA recommended defining ``suitable 
lamp'' to mean ``a circuit tester with an input voltage range of 50 VDC 
minimum, that is one of the following types: an incandescent lamp, LED 
indicator, buzzer, or Voltmeter.'' EMA stated that the specification 
for the voltage supply should be changed such that the vehicle's own 
voltage of 12 or 24 volts could be used for the indicator lamp. The 
commenter's definition does not specify an upper limit for the voltage 
and seemingly contradicts its request to allow use of the vehicle's own 
power supply. The voltage range of 40-50 volts is specified in 
S7.3.1(c) to ensure sufficient current in the circuit that can be 
detected by the lamp, while also ensuring the current is not 
sufficiently high to pose a safety risk to testing personnel. The 
purpose of the lamp is merely to provide a quick visual indication of 
contact with high voltage sources. The agency believes that as long as 
a lamp compatible with the voltage supply of 40-50 volts is used, there 
is no need to specify the type of lamp. The regulatory text in FMVSS 
No. 305a S7.3 was adopted from S9 in FMVSS No. 305, which has been 
effective since 2017, and is the same as that in GTR No. 20 and UNECE 
R100. The agency will further assess EMA's recommendations regarding 
the test procedure for direct contact protection and will consider 
updates to the regulatory text later, if warranted. At this time, NHTSA 
is adopting the test procedure for direct contact protection currently 
in FMVSS No. 305 and proposed in the NPRM for inclusion in FMVSS No. 
305a.
    3. Definition and Use of Nominal Voltage: EMA requested defining 
and using the term ``nominal voltage,'' instead of ``working voltage,'' 
for determining voltage in S7.1.2 of FMVSS No. 305a. EMA provided a 
definition of ``nominal voltage'' to mean a value that represents the 
typical or midpoint of a battery's maximum operating voltage and the 
minimum operating voltage over its charge and discharge cycle. NHTSA is 
not making this requested change in the final rule. The agency notes 
that the term ``working voltage'' and method of determining voltage are 
adopted from FMVSS No. 305 and have been effective since 2010. We 
believe the term ``working voltage'' is appropriate because it 
evaluates whether a component in the electric power train is a high 
voltage source when the vehicle is fully charged. Additionally, the 
singular instance of ``nominal voltage'' in S12.2 of the NPRM 
regulatory text has been changed to ``working voltage'' for 
consistency.
    4. Time limit for activating warning alerting driver to loss of 
electrical

[[Page 104345]]

isolation: For the loss of electrical isolation warning in S6.4, EMA 
suggested adding a time limit: ``The maximum time allowed to activate 
visual warning lamp shall be [less than] 1 minute when tested per 
S7.4.'' NHTSA did not include a time limit for the warning to activate 
when there is a loss in electrical isolation, which is consistent with 
other warning requirements in FMVSSs, e.g., the seat belt warning in 
FMVSS No. 208, ``Occupant crash protection.'' Activation of the warning 
is assessed visually by test personnel when loss in electrical 
isolation is simulated in accordance with S7.4.
    5. Typographical Error in figure 7b: EMA requested changing the 
phrase, ``chamber all edges,'' to ``chamfer all edges,'' in figure 7b. 
Jointed Test Finger IPXXB, of the regulatory text. This final rule 
corrects the typographical error in figure 7b.
    6. Voltmeter resistance in S7.1 of FMVSS No. 305a: EMA noted that 
the proposed S7.1 of FMVSS No. 305a specifies the voltmeter internal 
resistance be at least 10 MW and that it should be changed to 10 
M[Omega]. The regulatory text in the April 2024 NPRM correctly 
specifies the voltmeter resistance in M[Omega] and so no change is made 
in the final rule regulatory text.
    7. Exclusion of certain high voltage sources from electrical 
isolation requirements: MEMA requested clarifying that the exclusion in 
S6.3.2 also applies to pulsating DC voltages of less than 60 VDC in 
cases where there is no change in polarity. The September 2017 final 
rule \48\ updating FMVSS No. 305 excluded 48 V systems that are 
connected to the electrical chassis from electrical isolation 
requirements. In 48 V systems, the AC-DC inverter converts the DC 
current from the 48 V battery into AC for the 3-phase AC motor. The 
voltage between the electrical chassis and each of the phases of the AC 
electric motor is switched DC voltage (voltage between 0 and 48 volts). 
Because that voltage is less than 60 volts, it is considered low DC 
voltage under FMVSS No. 305. However, the voltage between two phases of 
the AC motor is AC, and may be slightly greater than 30 VAC under 
certain circumstances, which can be considered a high voltage AC source 
under the standard. However, the physical barrier protection (both 
direct and indirect contact protection) around the AC motor, and around 
cables from the inverter to the motor, would mitigate human contact 
with these AC high voltage sources, and thereby mitigate the likelihood 
of electric shock. In the 21st meeting of the working group developing 
GTR No. 20 Phase 2, the European Association of Automotive Suppliers 
(CLEPA) provided a rationale \49\ for also excluding pulsating DC high 
voltage sources with working voltage of 60 VDC or less where there is 
no change in polarity from electrical isolation requirements so as to 
accommodate 48 V air-cooled motor generators in the electric power 
train. NHTSA agrees with this rationale for this exclusion of pulsating 
DC high voltage sources with no change in polarity and with working 
voltage of 60 VDC or less from the electrical isolation requirements of 
S6.3.1 of FMVSS No. 305a.\50\ The regulatory text has been modified to 
provide this clarification.
---------------------------------------------------------------------------

    \48\ 82 FR 44945 (Sept. 27, 2017).
    \49\ See https://wiki.unece.org/download/attachments/117508721/EVS21-K01%20%5BCLEPA%5DR100-3%2048V%20Issue.pptx?api=v2.
    \50\ Section 5.3.4.1 of IEC TS 60479-2, ``Effects of current on 
human beings and livestock--Part 2,'' available at https://webstore.iec.ch/publication/63392, states that for combination of DC 
and AC voltage sources where there is no change in polarity, half 
the peak voltage can be used for determining electric shock risk. 
Because the risk of electric shock for 30 VAC is the same as 60 VDC, 
pulsating DC voltages less than or equal to 60 VDC pose no 
additional risk and can also be excluded from the electrical 
isolation requirement. The direct and indirect contact protection 
requirements further mitigate the risk of electric shock.
---------------------------------------------------------------------------

e. Static Rollover

Comments Received
    Tesla requested that NHTSA reconsider the static rollover test 
requirement, given the current state of EV batteries compared to older 
lead-acid batteries.
Agency Response
    The agency believes that there is merit in the static rollover test 
requirement, consistent with other FMVSS requirements. In addition, the 
agency is retaining requirements pertaining to electrolyte leakage for 
REESS with liquid electrolyte.

VI. Rulemaking Analyses and Notices

Executive Order 12866, Executive Order 14094, Executive Order 13563, 
and DOT Order Regulatory Policies and Procedures

    NHTSA has considered the impact of this rulemaking action under 
Executive Orders 12866, 14094, and 13563, DOT Order 2100.6A and the 
Department of Transportation's regulatory policies and procedures. The 
final rule is not considered to be significant under the Department of 
Transportation's regulatory policies and procedures. 44 FR 11034 (Feb. 
26, 1979). This action was not reviewed by the Office of Management and 
Budget under E.O. 12866.
    This final rule issues FMVSS No. 305a and Part 561 to update and 
expand the requirements that are in FMVSS No. 305. Most of GTR No. 20 
has already been adopted into FMVSS No. 305; this final rule completes 
the process by expanding FMVSS No. 305's applicability to heavy 
vehicles and by adopting the GTR's requirements for the REESS. Because 
there is widespread conformance with the requirements that would apply 
to existing vehicles, we anticipate no costs or benefits associated 
with this rulemaking.
    This final rule also requires that electric vehicle manufacturers 
submit standardized emergency response information to a NHTSA central 
depository, to assist first and second responders. A comprehensive list 
of pertinent vehicle-specific rescue information at a central location 
will enable first and second responders to respond to emergencies as 
quickly and safely as possible. Currently, electric vehicle 
manufacturers voluntarily upload emergency response information to the 
National Fire Protection Association's training site, so manufacturers 
are already providing vehicle-specific emergency response information. 
Under Part 561, manufacturers will submit ERGs and rescue sheets to 
NHTSA instead. We anticipate no additional costs by the manufacturers.

Regulatory Flexibility Act

    The Regulatory Flexibility Act of 1980 (5 U.S.C. 601 et seq.) 
(``the Act'') requires agencies to evaluate the potential effects of 
their proposed and final rules on small businesses, small 
organizations, and small Government jurisdictions. The Small Business 
Administration's regulations at 13 CFR part 121 define a small 
business, in part, as a business entity ``which operates primarily 
within the United States.'' (13 CFR 121.105(a)).
    The Act requires agencies to prepare and make available an initial 
and final regulatory flexibility analysis (RFA) describing the impact 
of proposed and final rules on small entities. An RFA is not required 
if the head of the agency certifies that the proposed or final rule 
will not have a significant impact on a substantial number of small 
entities. The head of the agency has made such a certification with 
regard to this final rule.
    The factual basis for the certification (5 U.S.C. 605(b)) is set 
forth below. Although the agency is not required to issue an initial 
regulatory flexibility analysis, this section discusses many of

[[Page 104346]]

the issues that an initial regulatory flexibility analysis would 
address.
    Section 603(b) of the Act specifies the content of an RFA. Each RFA 
must contain:
    1. A description of the reasons why action by the agency is being 
considered;
    2. A succinct statement of the objectives of, and legal basis for, 
a final rule;
    3. A description of and, where feasible, an estimate of the number 
of small entities to which the final rule will apply;
    4. A description of the projected reporting, recording keeping and 
other compliance requirements of a final rule, including an estimate of 
the classes of small entities that will be subject to the requirement 
and the type of professional skills necessary for preparation of the 
report or record;
    5. An identification, to the extent practicable, of all relevant 
Federal rules which may duplicate, overlap or conflict with the final 
rule;
    6. Each final regulatory flexibility analysis shall also contain a 
description of any significant alternatives to the final rule which 
accomplish the stated objectives of applicable statutes and which 
minimize any significant economic impact of the final rule on small 
entities.
    A description of the reason why action by the agency is being 
considered and the objectives of, and legal basis for, the final rule 
are discussed at length earlier in this document.
    This final rule will directly affect manufacturers subject to FMVSS 
No. 305a and Part 561. The Small Business Administration's size 
standard regulation at 13 CFR part 121, ``Small business size 
regulations,'' prescribes small business size standards by North 
American Industry Classification System (NAICS) codes. NAICS code 
336211, Motor Vehicle Body Manufacturing, prescribes a small business 
size standard of 1,000 or fewer employees. NAICS code 336390, Other 
Motor Vehicle Parts Manufacturing, prescribes a small business size 
standard of 1,000 or fewer employees. Most motor vehicle manufacturers 
would not qualify as a small business.
    NHTSA is aware of 3 small manufacturers of light and heavy electric 
vehicles. NHTSA believes that this rule will not have a significant 
economic impact on these manufacturers for the following reasons. 
First, small manufacturers of light electric vehicles are already 
subject to the electric vehicle safety requirements of FMVSS No. 305 
and have been certifying compliance to the standard for years. They are 
familiar with FMVSS requirements for electric vehicle safety, know how 
to assess the conformance of their vehicles with the requirements, and 
know how to certify their vehicles to the FMVSS. The new requirements 
for the REESS are manageable because the overcharge, over-discharge, 
over-current, over-temperature, and external short-circuit tests are 
non-destructive tests and can be conducted in serial order. The 
documentation requirements for safety risk mitigation associated with 
charging and discharging during cold temperature, safety risk 
mitigation associated with an internal short circuit in a single cell 
of a REESS, warning for a thermal event, and warning in the event of a 
malfunction of the vehicle controls that manage REESS safe operation 
are not design restrictive and add minimal cost. The documentation 
requirements simply ask manufacturers to describe to NHTSA how they 
have assessed certain safety risks and mitigated them.
    Second, there already is widespread voluntary compliance by the 
manufacturers with GTR No. 20, which is also aligned with industry 
standards. Therefore, there will be only a minor economic impact.
    Finally, although the final certification would be made by the 
manufacturer, this final rule allows one additional year for small 
volume manufacturers, final-stage manufacturers, and alterers to 
comply. This approach is similar to the approach NHTSA has taken in 
other rulemakings in recognition of manufacturing differences between 
larger and smaller manufacturers. NHTSA anticipates that EV components 
meeting FMVSS No. 305a will be developed by vehicle designers and 
suppliers and integrated into the fleets of larger vehicle 
manufacturers first, before small manufacturers. This final rule 
provides smaller manufacturers flexibility, so they have time to obtain 
the equipment and work with the suppliers after the demands of the 
larger manufacturers are met.
    This final rule applies to heavy vehicles, so this NPRM would also 
affect manufacturers of vehicles of over 4,536 kg (10,000 lb) GVWR, 
some of which may be final-stage manufacturers.\51\ According to the 
U.S. Census, there are 570 small businesses in body manufacturing for 
light, medium, and heavy-duty classes. However, it is NHTSA's 
understanding that these small entities rarely make modifications to a 
vehicle's REESS system and instead rely upon the pass-through 
certification provided by the first-stage manufacturer, which is not 
typically a small business. The same is true for alterers, which are 
manufacturers that obtain and alter a complete vehicle prior to the 
vehicle's first sale to a consumer.\52\ Furthermore, even if the final-
stage manufacturer or alterer must make the certification 
independently, as explained above this certification responsibility is 
manageable. The requirements do not involve crash testing (except for 
heavy school buses, as discussed below), and conformance with the 
requirements can be assessed relatively simply in a laboratory setting. 
And finally, this rule further accommodates final-stage manufacturers 
and alterers by providing them an additional year before compliance is 
required.\53\ For the reasons above, NHTSA does not believe that the 
economic impacts on small entities will be significant.
---------------------------------------------------------------------------

    \51\ Final-stage manufacturers produce vehicles by obtaining an 
incomplete vehicle (comprising the chassis and other associated 
parts) manufactured by an incomplete vehicle manufacturer, which is 
typically a large manufacturer. The final-stage manufacturer 
produces a vehicle by installing the vehicle body on the incomplete 
vehicle. The final-stage manufacturer typically certifies a complete 
vehicle by staying within manufacturing instructions provided by the 
incomplete vehicle manufacturer.
    \52\ Alterers certify that the vehicle was altered by them and 
as altered conforms to all applicable FMVSS, bumper, and theft 
prevention standards affected by the alteration.
    \53\ See 49 CFR 571.8(b).
---------------------------------------------------------------------------

    With regard to the crash test requirement for small manufacturers 
of heavy school buses, the additional requirement is for heavy school 
buses with high voltage electric propulsion systems to meet post-crash 
electrical safety requirements when impacted by the moving contoured 
barrier specified in FMVSS No. 301. This requirement does not require 
additional crash testing and aligns the applicability of FMVSS No. 305a 
with those of FMVSS Nos. 301 and 303. Per FMVSS No. 301 and FMVSS No. 
303, heavy school buses (school buses with a GVWR greater than 4,536 
kg) using conventional fuel or compressed natural gas for propulsion 
are required to maintain fuel system integrity in a crash test where 
the moving contoured barrier specified in FMVSS No. 301 traveling at 
any speed up to 48 km/h impacts the school bus at any point and angle. 
These requirements ensure post-crash safety to maintain the current 
high safety standards for school buses. Finally, this rule accommodates 
small manufacturers and final stage manufacturers of heavy school buses 
by providing them an additional year before compliance is required. For 
the reasons above, NHTSA

[[Page 104347]]

does not believe that the economic impacts of this rule on small 
entities will be significant.

National Environmental Policy Act

    NHTSA has analyzed this rule for the purposes of the National 
Environmental Policy Act. In accordance with 49 CFR 1.81, 42 U.S.C. 
4336, and DOT NEPA Order 5610.1C, NHTSA has determined that this rule 
is categorically excluded pursuant to 23 CFR 771.118(c)(4) (planning 
and administrative activities, such as promulgation of rules, that do 
not involve or lead directly to construction). This rulemaking, which 
establishes Federal Motor Vehicle Safety Standard (FMVSS) No. 305a, 
``Electric-powered vehicles: Electrolyte spillage and electrical shock 
protection,'' to update and replace FMVSS No.305 and to include 
performance requirements for propulsion batteries for light and heavy 
vehicles, and which establishes a new regulation, Part 561, 
``Documentation for Electric-powered Vehicles,'' that requires 
manufactures to compile risk mitigation documentation and submit 
standardized emergency response information to assist first and second 
responders handling electric vehicles, is not anticipated to result in 
any environmental impacts, and there are no extraordinary circumstances 
present in connection with this rulemaking.

Executive Order 13132 (Federalism)

    NHTSA has examined this rule pursuant to Executive Order 13132 (64 
FR 43255; Aug. 10, 1999) and concluded that no additional consultation 
with States, local governments, or their representatives is mandated 
beyond the rulemaking process. The agency has concluded that the rule 
does not have sufficient federalism implications to warrant 
consultation with State and local officials or the preparation of a 
federalism summary impact statement. The rule does not have 
``substantial direct effects on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government.''
    NHTSA rules can have preemptive effect in two ways. First, the 
National Traffic and Motor Vehicle Safety Act contains an express 
preemption provision: When a motor vehicle safety standard is in effect 
under this chapter, a State or a political subdivision of a State may 
prescribe or continue in effect a standard applicable to the same 
aspect of performance of a motor vehicle or motor vehicle equipment 
only if the standard is identical to the standard prescribed under this 
chapter. 49 U.S.C. 30103(b)(1). It is this statutory command that 
preempts any non-identical State legislative and administrative law 
address the same aspect of performance. The express preemption 
provision described above is subject to a savings clause under which 
``[c]ompliance with a motor vehicle safety standard prescribed under 
this chapter does not exempt a person from liability at common law.'' 
49 U.S.C. 30103(e). Pursuant to this provision, State common law tort 
causes of action against motor vehicle manufacturers that might 
otherwise be preempted by the express preemption provision are 
generally preserved.
    NHTSA rules can also preempt State law if complying with the FMVSS 
would render the motor vehicle manufacturers liable under State tort 
law. Because most NHTSA standards established by an FMVSS are minimum 
standards, a State common law tort cause of action that seeks to impose 
a higher standard on motor vehicle manufacturers will generally not be 
preempted. However, if and when such a conflict does exist--for 
example, when the standard at issue is both a minimum and a maximum 
standard--the State common law tort cause of action is impliedly 
preempted. See Geier v. American Honda Motor Co., 529 U.S. 861 (2000).
    Pursuant to Executive Order 13132, NHTSA has considered whether 
this rule could or should preempt State common law causes of action. 
The agency's ability to announce its conclusion regarding the 
preemptive effect of one of its rules reduces the likelihood that 
preemption will be an issue in any subsequent tort litigation. To this 
end, the agency has examined the nature (e.g., the language and 
structure of the regulatory text) and objectives of this rule and finds 
this rule, like many NHTSA rules, would prescribe only a minimum safety 
standard. As such, NHTSA does not intend that this rule preempt state 
tort law that would effectively impose a higher standard on motor 
vehicle manufacturers than that established by this rule. Establishment 
of a higher standard by means of State tort law would not conflict with 
the standards in this final rule. Without any conflict, there could not 
be any implied preemption of a State common law tort cause of action.

Executive Order 12988 (Civil Justice Reform)

    With respect to the review of the promulgation of a new regulation, 
section 3(b) of Executive Order 12988, ``Civil Justice Reform'' (61 FR 
4729, Feb. 7, 1996), requires that Executive agencies make every 
reasonable effort to ensure that the regulation: (1) Clearly specifies 
the preemptive effect; (2) clearly specifies the effect on existing 
Federal law or regulation; (3) provides a clear legal standard for 
affected conduct, while promoting simplification and burden reduction; 
(4) clearly specifies the retroactive effect, if any; (5) adequately 
defines key terms; and (6) addresses other important issues affecting 
clarity and general draftsmanship under any guidelines issued by the 
Attorney General. This document is consistent with that requirement.
    Pursuant to this Order, NHTSA notes as follows. The issue of 
preemption is discussed above. NHTSA notes further that there is no 
requirement that individuals submit a petition for reconsideration or 
pursue other administrative proceedings before they may file suit in 
court.

Executive Order 13045 (Protection of Children From Environmental Health 
and Safety Risk)

    Executive Order 13045 (62 FR 19885, April 23, 1997) applies to any 
rule that: (1) is determined to be ``economically significant'' as 
defined under E.O. 12866, and (2) concerns an environmental, health, or 
safety risk that NHTSA has reason to believe may have a 
disproportionate effect on children. If the regulatory action meets 
both criteria, we must evaluate the environmental health or safety 
effects of the planned rule on children and explain why the planned 
regulation is preferable to other potentially effective and reasonably 
feasible alternatives considered by us.
    This final rule is not subject to the Executive order because it is 
not economically significant as defined in E.O. 12866.

Privacy Act

    Please note that anyone is able to search the electronic form of 
all comments received into any of our dockets by the name of the 
individual submitting the comment (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 (65 FR 19477-78), or online at http://www.dot.gov/privacy.html.

Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et. seq., as added by 
the Small Business Regulatory Enforcement Fairness Act of 1996, 
generally provides that before a rule may take effect, the

[[Page 104348]]

agency promulgating the rule must submit a rule report, which includes 
a copy of the rule, to each House of the Congress and to the 
Comptroller General of the United States. NHTSA will submit a report 
containing this rule and other required information to the U.S. Senate, 
the U.S. House of Representatives, and the Comptroller General of the 
United States prior to publication of the rule in the Federal Register. 
This rule does not meet the criteria in 5 U.S.C. 804(2) to be 
considered a major rule. The rule will be effective sixty days after 
the date of publication in the Federal Register.

Paperwork Reduction Act

    Under the procedures established by the Paperwork Reduction Act of 
1995 (PRA) (44 U.S.C. 3501, et. seq.), Federal agencies must obtain 
approval from the OMB for each collection of information they conduct, 
sponsor, or require through regulations. A person is not required to 
respond to a collection of information by a Federal agency unless the 
collection displays a valid OMB control number. The Information 
Collection Request (ICR) for the new information collection described 
below has been forwarded to OMB for review and comment.
    The final rule has two types of new collection of information that 
are part of the Part 561 requirements: (1) Electric Vehicles: Rescue 
Sheets and Emergency Response Guides and (2) Electric Vehicles: REESS 
Thermal Propagation Safety Risk Analysis and Mitigation Documentation. 
NHTSA sought comment on the new information collection requirements in 
the NPRM published on April 15, 2024.\54\ There were no PRA-specific 
comments provided. NHTSA's response to the comments and the final 
rule's information collection requirements are discussed in sections 
IV.j-l above. As discussed, NHTSA is largely adopting the proposal with 
some changes. In accordance with the requirements of the PRA, NHTSA is 
resubmitting the ICR for this final rule. In the final rule, the 
emergency response information and four documentation requirements are 
added to the general regulation Part 561 rather than in the proposed 
FMVSS No. 305a, given that the documentation specifications are more 
akin to a disclosure requirement than a performance test. The estimated 
total burden of this collection is modified to account for the final 
rule's addition of the audio-visual warning for a thermal event in the 
REESS to be part of the documentation requirements that was not 
initially proposed in the NPRM. For each vehicle model, vehicle 
manufacturers will need an estimated 84 hours to complete the four 
documentation requirements (17 hours to complete the documentation for 
low temperature operation safety, 17 hours for the documentation about 
warning in the event of operational failure of REESS vehicle controls, 
17 hours for the documentation for thermal event warning, and 33 hours 
for the documentation covering thermal runaway due to internal short in 
a single cell of the REESS). After this rule's effective date, all 205 
vehicle models are expected to compile the necessary information to 
meet the four documentation requirements. The total estimated annual 
burden hours for the four documentation requirements is 17,220 hours 
(205 vehicle models x 84 hours). The previous total estimated burden 
hours for the three documentation requirements in the NPRM was 13,735 
hours (205 vehicle models x 67 hours).
---------------------------------------------------------------------------

    \54\ 89 FR 26704.
---------------------------------------------------------------------------

    The estimated total annual burden hours for the emergency response 
information was slightly decreased to approximately 2,335 hours from 
the original estimation of 2,506 burden hours. Because rescue sheets 
and emergency response guides often cover several model years, the 
percentage of models that would need new or updates to existing or 
previously submitted rescue sheets and ERGs is likely to decrease after 
the second year of the effective date. With additional documentation 
requirements from the final rule, the total estimated annual burden 
hours for the two new types of information collection is estimated to 
be 19,565 burden hours.
    In the NPRM, NHTSA originally included labor costs under the burden 
cost calculation. NHTSA now estimates that there will be no costs to 
respondents other than the labor costs from the corresponding burden 
hours of compiling the information. Therefore, the total annual burden 
cost has now been corrected to be $0.
    The OMB control numbers for NHTSA regulations are displayed at 49 
CFR part 509. When OMB approves this ICR, the agency will announce that 
approval in the Federal Register and, as appropriate, display the OMB 
control number on the applicable collection instruments and publish a 
technical amendment to 49 CFR part 509 to display the OMB control 
number for the approved information collection activities contained in 
this final rule.

National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (NTTAA), Public Law 104-113, as amended by Public Law 107-
107 (15 U.S.C. 272), directs the agency to evaluate and use voluntary 
consensus standards in its regulatory activities unless doing so would 
be inconsistent with applicable law or is otherwise impractical. 
Voluntary consensus standards are technical standards (e.g., materials 
specifications, test methods, sampling procedures, and business 
practices) that are developed or adopted by voluntary consensus 
standards bodies, such as the Society of Automotive Engineers (SAE). 
The NTTAA directs us to provide Congress (through OMB) with 
explanations when the agency decides not to use available and 
potentially applicable voluntary consensus standards.
    This final rule is consistent with the goals of the NTTAA. This 
rule adopts a global consensus standard. The GTR was developed by a 
global regulatory body and is designed to increase global harmonization 
of differing vehicle standards. The GTR leverages the expertise of 
governments in developing a vehicle standard to increase electric 
vehicle safety, including the performance of the REESS. NHTSA's 
consideration of GTR No. 20 accords with the principles of NTTAA as 
NHTSA's consideration of an established, proven global technical 
regulation has reduced the need for NHTSA to expend significant agency 
resources on the same safety need addressed by GTR No. 20.
    In addition, the following voluntary consensus standards have been 
used in developing this final rule:
     ISO-6469-1: Amendment 1 2022-11.
     ISO-26262:2018.
     ISO 17840-1:2022(E), ``Road vehicles--Information for 
first and second responders--Part 1: Rescue sheet for passenger cars 
and light commercial vehicles,'' Second Edition, February 2022.
     ISO 17840-2:2019(E), ``Road vehicles--Information for 
first and second responders--Part 2: Rescue sheet for buses, coaches 
and heavy commercial vehicles,'' First edition, April 201.
     ISO 17840-3:2019(E), ``Road vehicles--Information for 
first and second responders--Part 3: Emergency response guide 
template,'' First Edition, April 2019.

[[Page 104349]]

Unfunded Mandates Reform Act

    Section 202 of the Unfunded Mandates Reform Act of 1995 (UMRA), 
Public Law 104-4, requires Federal agencies to prepare a written 
assessment of the costs, benefits, and other effects of proposed or 
final rules that include a Federal mandate likely to result in the 
expenditure by State, local, or Tribal governments, in the aggregate, 
or by the private sector, of more than $100 million annually (adjusted 
for inflation with base year of 1995). Adjusting this amount by the 
implicit gross domestic product price deflator for the year 2022 
results in $177 million (111.416/75.324 = 1.48). This rule will not 
result in a cost of $177 million or more to State, local, or Tribal 
governments, in the aggregate, or the private sector. Thus, this rule 
is not subject to the requirements of sections 202 of the UMRA.

Executive Order 13609 (Promoting Regulatory Cooperation)

    The policy statement in section 1 of Executive Order 13609 
provides, in part: The regulatory approaches taken by foreign 
governments may differ from those taken by U.S. regulatory agencies to 
address similar issues. In some cases, the differences between the 
regulatory approaches of U.S. agencies and those of their foreign 
counterparts might not be necessary and might impair the ability of 
American businesses to export and compete internationally. In meeting 
shared challenges involving health, safety, labor, security, 
environmental, and other issues, international regulatory cooperation 
can identify approaches that are at least as protective as those that 
are or would be adopted in the absence of such cooperation. 
International regulatory cooperation can also reduce, eliminate, or 
prevent unnecessary differences in regulatory requirements.
    The agency participated in the development of GTR No. 20 to 
harmonize the standards of electric vehicles. As a signatory member, 
NHTSA is incorporating electrical safety requirements and options 
specified in GTR No. 20 with modifications into FMVSS No. 305a and Part 
561.

Incorporation by Reference

    Under regulations issued by the Office of the Federal Register (1 
CFR 51.5(a)), an agency must summarize in the preamble of a proposed or 
final rule the material it incorporates by reference and discuss the 
ways the material is reasonably available to interested parties or how 
the agency worked to make materials available to interested parties.
    In this final rule, NHTSA incorporates by reference three documents 
into the Code of Federal Regulations. The first document is ISO 17840-
1:2022(E), ``Road vehicles--Information for first and second 
responders--Part 1: Rescue sheet for passenger cars and light 
commercial vehicles.'' ISO 17840-1:2022(E) standardizes the content and 
layout of rescue sheets for passenger cars and light commercial 
vehicles.
    The second document is ISO 17840-2:2019(E), ``Road vehicles--
Information for first and second responders--Part 2: Rescue sheet for 
buses, coaches and heavy commercial vehicles.'' ISO 17840-2:2019(E) 
standardizes the rescue sheets for buses, coaches, and heavy commercial 
vehicles.
    The third document is ISO 17840-3:2019(E), ``Road vehicles--
Information for first and second responders--Part 3: Emergency response 
guide template.'' ISO 17840-3:2019(E) establishes a template and 
defines the general content for manufacturers' emergency response 
guides for all vehicle types.
    All three documents are incorporated by reference solely to specify 
the layout and format of the rescue sheets and emergency response 
guides. The ISO material is available for review at NHTSA and is 
available for purchase from ISO.\55\
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    \55\ ISO standards may be purchased from the ANSI webstore 
https://webstore.ansi.org/.
---------------------------------------------------------------------------

Severability

    The issue of severability of FMVSSs is addressed in 49 CFR 571.9. 
It provides that if any FMVSS or its application to any person or 
circumstance is held invalid, the remainder of the part and the 
application of that standard to other persons or circumstances is 
unaffected.

Regulation Identifier Number

    The Department of Transportation assigns a regulation identifier 
number (RIN) to each regulatory action listed in the Unified Agenda of 
Federal Regulations. The Regulatory Information Service Center 
publishes the Unified Agenda in April and October of each year. You may 
use the RIN contained in the heading at the beginning of this document 
to find this action in the Unified Agenda.

Rulemaking Summary, 5 U.S.C. 553(b)(4)

    As required by 5 U.S.C. 553(b)(4), a summary of this rule can be 
found in the Abstract section of the Department's Unified Agenda entry 
for this rulemaking at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM43.

Plain Language

    Executive Order 12866 requires each agency to write all rules in 
plain language. Application of the principles of plain language 
includes consideration of the following questions:
     Have we organized the material to suit the public's needs?
     Are the requirements in the rule clearly stated?
     Does the rule contain technical language or jargon that 
isn't clear?
     Would a different format (grouping and order of sections, 
use of headings, paragraphing) make the rule easier to understand?
     Would more (but shorter) sections be better?
     Could we improve clarity by adding tables, lists, or 
diagrams?
     What else could we do to make the rule easier to 
understand?
    If you have any responses to these questions, please write to us 
with your views.

Submission of Confidential Information

    You should submit a redacted ``public version'' of your comment 
(including redacted versions of any additional documents or 
attachments). This ``public version'' of your comment should contain 
only the portions for which no claim of confidential treatment is made 
and from which those portions for which confidential treatment is 
claimed has been redacted. See below for further instructions on how to 
do this.
    You also need to submit a request for confidential treatment 
directly to the Office of Chief Counsel. Requests for confidential 
treatment are governed by 49 CFR part 512. Your request must set forth 
the information specified in part 512. This information includes the 
materials for which confidentiality is being requested (as explained in 
more detail below); supporting information, pursuant to Sec.  512.8; 
and a certificate, pursuant to Sec.  512.4(b) and part 512, appendix A.
    You are required to submit to the Office of Chief Counsel one 
unredacted ``confidential version'' of the information for which you 
are seeking confidential treatment. Pursuant to Sec.  512.6, the words 
``ENTIRE PAGE CONFIDENTIAL BUSINESS INFORMATION'' or ``CONFIDENTIAL 
BUSINESS INFORMATION CONTAINED WITHIN BRACKETS'' (as applicable) must 
appear at the top of each page containing information claimed to be 
confidential. In the latter

[[Page 104350]]

situation, where not all information on the page is claimed to be 
confidential, identify each item of information for which 
confidentiality is requested within brackets: ``[ ].''
    You are also required to submit to the Office of Chief Counsel one 
redacted ``public version'' of the information for which you are 
seeking confidential treatment. Pursuant to Sec.  512.5(a)(2), the 
redacted ``public version'' should include redactions of any 
information for which you are seeking confidential treatment (i.e., the 
only information that should be unredacted is information for which you 
are not seeking confidential treatment).
    NHTSA is currently treating electronic submission as an acceptable 
method for submitting confidential business information to the agency 
under part 512. Please do not send a hardcopy of a request for 
confidential treatment to NHTSA's headquarters. The request should be 
sent to Dan Rabinovitz in the Office of the Chief Counsel at 
[email protected]. You may either submit your request via email 
or request a secure file transfer link. If you are submitting the 
request via email, please also email a courtesy copy of the request to 
K. Helena Sung at [email protected].

List of Subjects

49 CFR Part 561

    Imports, Incorporation by reference, Motor vehicles, Motor vehicle 
safety.

49 CFR Part 571

    Imports, Motor vehicles, Motor vehicle safety.

    In consideration of the foregoing, NHTSA amends 49 CFR chapter V as 
set forth below.

0
1. Add part 561 to read as follows:

PART 561--DOCUMENTATION FOR ELECTRIC-POWERED VEHICLES.

Sec.
561.1 Scope.
561.2 Purpose.
561.3 Application.
561.4 Matter incorporated by reference.
561.5 Definitions.
561.6 Rescue sheets and emergency response guides.
561.7 Documentation for low temperature operation safety.
561.8 Documentation of a visual warning for malfunction of vehicle 
controls that manage REESS operation.
561.9 Documentation of an audio-visual warning for a thermal event 
in the REESS.
561.10 Documentation for single cell thermal runaway and propagation 
safety risk mitigation.
561.11 Record retention.


    Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166; 
delegation of authority at 49 CFR 1.95.


Sec.  561.1  Scope.

    This part specifies requirements for the submission of standardized 
emergency response guides (ERGs) and rescue sheets for electric-powered 
vehicles. It also specifies requirements for other documentation, to be 
submitted to NHTSA upon request, addressing low temperature operation 
safety, warning in the event of malfunction of vehicle controls 
managing Rechargeable Electrical Energy Storage System (REESS) 
operations, warning in the case of a thermal event in the REESS, and 
safety risk mitigation for thermal runaway and propagation.


Sec.  561.2  Purpose.

    The purpose of this part is to ensure emergency response 
information is readily available for first and second responders 
regarding the safe handling of electric-powered vehicles and to ensure 
vehicle occupants are alerted to potentially hazardous conditions. The 
other documentation requirements are to ensure vehicle manufacturers 
identify and address safety risks associated with the electric 
propulsion system in addition to the requirements of part 571 of this 
chapter.


Sec.  561.3  Application.

    This part applies to passenger cars, multipurpose passenger 
vehicles, trucks, and buses that use electrical propulsion components 
with working voltages greater than 60 volts direct current (VDC) or 30 
volts alternating current (VAC), and whose speed attainable over a 
distance of 1.6 km on a paved level surface is more than 40 km/h.
    (a) Rescue sheets and emergency response guides requirements. 
Vehicles manufactured on or after December 22, 2025, are subject to 
Sec.  561.6.
    (b) Documentation requirements. (1) Vehicles with a gross vehicle 
weight rating of 4,536 kilograms (kg) or less manufactured on or after 
September 1, 2027, are subject to Sec. Sec.  561.7 through 561.10.
    (2) Vehicles with a gross vehicle weight rating over 4,536 
kilograms (kg) manufactured on or after September 1, 2028, are subject 
to Sec. Sec.  561.7 through 561.10.
    (3) The requirements Sec. Sec.  561.7 through 561.10 do not apply 
to small-volume manufacturers, final-stage manufacturers, and alterers 
of vehicles with a gross vehicle weight rating under 4,536 kilograms 
(kg) until one year after the date specified in paragraph (b)(1) of 
this section.
    (4) The requirements Sec. Sec.  561.7 through 561.10 do not apply 
to small-volume manufacturers, final-stage manufacturers, and alterers 
of vehicles with a gross vehicle weight rating over 4,536 kilograms 
(kg) until one year after the date specified in paragraph (b)(2) of 
this section.


Sec.  561.4   Matter incorporated by reference.

    The material listed in this section is incorporated by reference 
into this section with the approval of the Director of the Federal 
Register in accordance with 5 U.S.C. 522(a) and 1 CFR part 51. All 
approved incorporation by reference (IBR) material is available for 
inspection at the National Highway Traffic Safety Administration 
(NHTSA) or at the National Archives and Records Administration (NARA). 
Contact NHTSA at: 1200 New Jersey Avenue SE, Washington, DC 20590; 
(202) 366-2588; www.nhtsa.gov/about-nhtsa/electronic-reading-room. For 
information on the availability of this material at NARA, visit 
www.archives.gov/contact. The material may be obtained from the 
following paragraphs of this section.
    (a) International Organization for Standardization (ISO), 1, ch. de 
la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland; phone: + 41 22 
749 01 11; fax: + 41 22 733 34 30; website: www.iso.org.
    (1) ISO 17840-1:2022(E), Road vehicles--Information for first and 
second responders--Part 1: Rescue sheet for passenger cars and light 
commercial vehicles, Second Edition, February 2022, into Sec.  561.6.
    (2) ISO 17840-2:2019(E), Road vehicles--Information for first and 
second responders--Part 2: Rescue sheet for buses, coaches and heavy 
commercial vehicles, First edition, April 2019, into Sec.  561.6.
    (3) ISO 17840-3:2019(E), Road vehicles--Information for first and 
second responders--Part 3: Emergency response guide template, First 
Edition, April 2019, into Sec.  561.6.
    (b) [Reserved]


Sec.  561.5   Definitions.

    (a) Statutory definitions. All terms defined in section 30102 of 
the National Traffic and Motor Vehicle Safety Act (49 U.S.C. chapter 
301, et seq.) are used in their statutory meaning.
    (b) Motor vehicle safety standard definitions. All terms defined in 
49 CFR part 571 are used as defined therein.
    (c) Other definitions--
    Emergency response guide means a document containing in-depth 
vehicle-specific information related to fire,

[[Page 104351]]

submersion, leakage of fluids, towing, and storage of vehicles for 
first and second responders.
    First responder means a person with specialized training such as a 
law enforcement officer, paramedic, emergency medical technician, and/
or firefighter.
    Rescue sheet means an abbreviated version of an emergency response 
guide that gives quick information about a vehicle's construction, 
intended for use by first and second responders at the scene of a 
crash.
    Second responder means a worker who supports first responders by 
cleaning up a site, towing vehicles, and/or supporting services after 
an event requiring first responders.


Sec.  561.6   Rescue sheets and emergency response guides.

    (a) Rescue sheets. Prior to first vehicle sale or lease, vehicle 
manufacturers shall submit rescue sheets to NHTSA.
    (1) For vehicles with a GVWR less than or equal to 4,536 kg to 
which the requirement applies, submitted rescue sheets shall follow the 
layout and format in ISO-17840-1:2022(E) (incorporated by reference; 
see Sec.  561.4).
    (2) For vehicles with a GVWR greater than 4,536 kg to which the 
standard applies, the submitted rescue sheets shall follow the layout 
and format in ISO-17840-2:2019(E) (incorporated by reference; see Sec.  
561.4).
    (3) The rescue sheets shall provide information for first 
responders to extricate occupants.
    (b) Emergency response guides (ERGs). Prior to first vehicle sale 
or lease, vehicle manufacturers shall submit emergency response guides 
to NHTSA in accordance with the template layout and format in ISO-
17840-3:2019(E) (incorporated by reference; see Sec.  561.4). vehicles 
to which this requirement applies.
    (1) The ERGs shall provide in-depth information linked and aligned 
to the corresponding rescue sheet to support the quick and safe action 
of first responders and second responders.
    (2) The ERGs shall provide in-depth information related to electric 
vehicle fire, submersion, leakage of fluids, towing, transportation, 
and storage.
    (3) The ERGs shall provide information to assist first responders 
in extricating occupants.


Sec.  561.7   Documentation for low temperature operation safety.

    At NHTSA's request, each manufacturer shall submit documentation 
that includes the following:
    (a) The make, model, model year, and production dates of the 
vehicles to which the submitted documentation applies.
    (b) The lower temperature boundary for safe REESS operation in all 
vehicle operating modes.
    (c) A description and explanation of charge and discharge rates at 
the manufacturer specified lower temperature boundary for safe REESS 
operation.
    (d) A description of the method used to detect REESS temperature.
    (e) A system diagram with key components and subsystems involved in 
maintaining safe REESS charging and discharging operation for 
temperatures at or below the manufacturer specified lower temperature 
boundary for safe REESS operation.
    (f) A description of how the vehicle controls, ancillary equipment, 
and design features were validated and verified for maintaining safe 
REESS operations at or below the manufacturer specified lower 
temperature boundary for safe REESS operation.
    (g) Overall evaluation: A description of the final manufacturer 
review/audit process and results of any final review or audit 
evaluating the technical content and the completeness and verity of 
paragraphs (a) through (f) of this section.


Sec.  561.8   Documentation of a visual warning for malfunction of 
vehicle controls that manage REESS operation.

    At NHTSA's request, each manufacturer shall submit documentation 
that includes the following:
    (a) The make, model, model year, and production dates of the 
vehicles to which the submitted documentation applies.
    (b) A system diagram that identifies all the vehicle controls that 
manage REESS operation. The diagram must identify what components are 
used to generate a visual warning indicating malfunction of vehicle 
controls to conduct one or more basic REESS operations.
    (c) A written explanation describing the basic operation of the 
vehicle controls that manage REESS operation. The explanation must 
identify the components of the vehicle control system, provide 
description of their functions and capability to manage the REESS, and 
provide a logic diagram and description of conditions that would lead 
to triggering the telltale activation.
    (d) Validation results from tests to confirm the display of a 
visual warning in the presence of a malfunction of the vehicle controls 
which manage safe operation of the REESS.
    (e) Overall evaluation: A description of the final manufacturer 
review/audit process and results of the final review or audit which 
evaluated the technical content and the completeness and verity of 
paragraphs (a) through (d) of this section.


Sec.  561.9   Documentation of an audio-visual warning for a thermal 
event in the REESS.

    At NHTSA's request, each manufacturer shall submit documentation 
that includes the following:
    (a) The make, model, model year, and production dates of the 
vehicles to which the submitted documentation applies.
    (b) A system diagram of the thermal event warning system.
    (c) A written explanation describing the basic operation of the 
thermal event warning system. The explanation must identify the 
components of the thermal event warning system, provide descriptions of 
their functions and capability, and provide a logic diagram and 
description of conditions that would lead to triggering the warning 
activation.
    (d) Validation results from tests to confirm the activation of an 
audio-visual warning in the case of a thermal event in the REESS.
    (e) Overall evaluation: A description of the final manufacturer 
review/audit process and results of the final review or audit which 
evaluated the technical content and the completeness and verity of 
paragraphs (a) through (d) of this section.


Sec.  561.10   Documentation for single cell thermal runaway and 
propagation safety risk mitigation.

    The vehicle manufacturer shall make available to NHTSA, upon 
request, documentation demonstrating how the vehicle and its REESS are 
designed to mitigate the safety risks associated with thermal 
propagation resulting from a single cell thermal runaway due to an 
internal short within the cell. The documentation shall demonstrate 
thermal propagation safety risk mitigation for the vehicle in external 
charging mode, active driving possible mode, and parking mode. The 
documentation shall include the following:
    (a) Vehicle information. This part of the documentation shall 
identify the make, model, model year, and production dates of the 
vehicles to which the submitted documentation applies.
    (b) Part I: System analysis. This part of the documentation shall 
identify the conditions which could lead to single-cell thermal runaway 
due to an internal short-circuit in different vehicle

[[Page 104352]]

operational modes and allocate applicable functional units, components, 
and subsystems to each identified condition. This part shall include:
    (1) A system diagram and a description of all relevant physical 
systems and components of the REESS, including information about the 
cell type and electrical configuration, cell chemistry, electrical 
capacity, voltage, current limits during charging and discharging, and 
thermal limits of the components that are critical for thermal 
propagation safety.
    (2) A system diagram, operational description of sensors, 
components, functional units relevant to single-cell thermal runaway 
due to internal short-circuit and thermal propagation, and the 
interrelationship among the identified sensors, components, and 
functional units;
    (3) A description of conditions under which a single-cell thermal 
runaway and propagation event due to an internal short-circuit could 
occur;
    (4) A description of how the identified conditions were allocated 
to each identified component, functional unit, and subsystem;
    (5) A description of the process used to review the identified 
conditions and their allocation to the identified sensors, components, 
and functional units, for completeness and validity; and
    (6) A description of the warning or notification system before the 
thermal runaway occurs, including a description of the detection 
technology and mitigation strategies, if any.
    (c) Part II: Safety risk assessment and mitigation process. This 
part of the documentation shall identify thermal propagation safety 
risk mitigation strategies for identified conditions leading to single 
cell thermal runaway in Part I and include:
    (1) A description of the safety risks and safety risk mitigation 
strategies, and how these were identified, and
    (2) A description of how each risk mitigation strategy manages, 
mitigates, or prevents the identified safety risks.
    (3) Safety risk mitigation strategies identified should include 
those that mitigate the risk of single cell thermal runaway due to an 
internal short and mitigate the occurrence of thermal propagation due 
to single-cell thermal runaway resulting from an internal short-circuit 
within the cell.
    (d) Part III: Verification and validation of risk mitigation 
strategies. This part of the documentation pertains to verification 
that the manufacturer identified safety risks and considered safety 
risk mitigation strategies and shall include:
    (1) A description of how each risk mitigation strategy was verified 
and validated for effectiveness,
    (2) A description of the verification and validation results for 
each risk mitigation strategy, and
    (3) A description of and results from the vehicle level assessment.
    (e) Part IV: Overall evaluation of risk mitigation. This part of 
the documentation summarizes the vehicle design and manufacturing 
strategies and their validation to mitigate the safety risks associated 
with thermal propagation due to single cell thermal runaway resulting 
from internal short within a cell. This part shall include a 
description of the final manufacturer review/audit process and results 
of the final review or audit evaluating the technical content and the 
completeness and verity of paragraphs (a) through (d) of this section.


Sec.  561.11  Record retention.

    Each applicable manufacturer shall maintain the information 
specified in Sec. Sec.  561.7 through 561.10 for the documentation 
requirements for a period of five years from the date of manufacture.

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

0
2. The authority citation for part 571 continues to read as follows:

    Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166; 
delegation of authority at 49 CFR 1.95.


0
3. Section 571.305 is amended by revising the section heading and S3 to 
read as follows:


Sec.  571.305   Standard No. 305; electric-powered vehicles: 
electrolyte spillage and electrical shock protection; applicable unless 
a vehicle is certified to Sec.  571.305a.

* * * * *
    S3. Application. This standard applies to passenger cars, and to 
multipurpose passenger vehicles, trucks, and buses with a gross vehicle 
weight rating (GVWR) of 4,536 kilograms (kg) or less, that use 
electrical propulsion components with working voltages greater than 60 
volts direct current (VDC) or 30 volts alternating current (VAC), and 
whose speed attainable over a distance of 1.6 km on a paved level 
surface is more than 40 km/h, that are manufactured before September 1, 
2027.
* * * * *

0
4. Section 571.305a is added to read as follows:


Sec.  571.305a   Standard No. 305a; electric-powered vehicles: Electric 
powertrain integrity; mandatory applicability begins on September 1, 
2027.

    S1. Scope. This standard specifies requirements for protection from 
harmful electric shock, fire, explosion, and gas venting during normal 
vehicle operation and during and after a crash.
    S2. Purpose. The purpose of this standard is to reduce deaths and 
injuries during normal vehicle operations and during and after a crash 
that occur because of electrolyte leakage, intrusion of electric energy 
storage/conversion devices into the occupant compartment, electric 
shock, fire, explosion, and gas venting, including deaths and injuries 
due to driver error.
    S3. Application. (a) This standard applies to passenger cars, 
multipurpose passenger vehicles, trucks, and buses that use electrical 
propulsion components with working voltages greater than 60 volts 
direct current (VDC) or 30 volts alternating current (VAC), and whose 
speed attainable over a distance of 1.6 km on a paved level surface is 
more than 40 km/h.
    (b) Mandatory applicability begins 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 in this paragraph (b).
    S4. Definitions.
    Active driving possible mode means the vehicle mode when 
application of pressure to the accelerator pedal (or activation of an 
equivalent control) or release of the brake system causes the electric 
power train to move the vehicle.
    Automatic disconnect means a device that when triggered, 
conductively separates a high voltage source from the electric power 
train or the rest of the electric power train.
    Breakout harness means connector wires that are connected for 
testing purposes to the REESS on the traction side of the automatic 
disconnect.
    Capacitor means a device used to store electrical energy, 
consisting of one or more pairs of conductors separated by an 
insulator: x-capacitors are connected between electrical mains or 
neutral and y-capacitors are connected between a main to ground.
    Charge connector is a conductive device that, by insertion into a 
vehicle charge inlet, establishes an electrical connection of the 
vehicle to an external electric power supply for the purpose of 
transferring energy.

[[Page 104353]]

    Chassis dynamometer means a mechanical device that uses one or more 
fixed roller assemblies to simulate different road conditions within a 
controlled environment and is used for a wide variety of vehicle 
testing.
    Connector means a device providing mechanical connection and 
disconnection of high voltage electrical conductors to a suitable 
mating component, including its housing.
    n C Rate means the constant current of the REESS, which takes 1/n 
hours to charge or discharge the REESS between 0 and 100 percent state 
of charge.
    Direct contact is the contact of any person or persons with high 
voltage live parts.
    Electric energy storage device means a high voltage source that 
stores energy for vehicle propulsion. This includes, but is not limited 
to, a high voltage battery or battery pack, rechargeable energy storage 
device, and capacitor module.
    Electric energy storage/conversion device means a high voltage 
source that stores or converts energy for vehicle propulsion. This 
includes, but is not limited to, a high voltage battery or battery 
pack, fuel cell stack, rechargeable energy storage device, and 
capacitor module.
    Electric energy storage/conversion system means an assembly of 
electrical components that stores or converts electrical energy for 
vehicle propulsion. This includes, but is not limited to, high voltage 
batteries or battery packs, fuel cell stacks, rechargeable energy 
storage systems, capacitor modules, inverters, interconnects, and 
venting systems.
    Electric power train means an assembly of electrically connected 
components which includes, but is not limited to, electric energy 
storage/conversion systems and propulsion systems.
    Electrical chassis means conductive parts of the vehicle whose 
electrical potential is taken as reference and which are:
    (1) Conductively linked together, and
    (2) Not high voltage sources during normal vehicle operation.
    Electrical isolation of a high voltage source in the vehicle means 
the electrical resistance between the high voltage source and any of 
the vehicle's electrical chassis divided by the working voltage of the 
high voltage source.
    Electrical protection barrier is the part providing protection 
against direct contact with high voltage live parts from any direction 
of access.
    Electrolyte leakage means the escape of liquid electrolyte from the 
REESS.
    Exposed conductive part is a conductive part that can be touched 
under the provisions of the IPXXB protection degree and that is not 
normally energized, but that can become electrically energized under 
isolation fault conditions. This includes parts under a cover if the 
cover can be removed without using tools.
    External charging mode means the vehicle mode when the REESS is 
charging with external electric power supply connected through the 
charge connector to the vehicle charge inlet.
    External electric power supply is a power supply external to the 
vehicle that provides electric power to charge the electric energy 
storage device in the vehicle through the charge connector.
    Fuel cell system is a system containing the fuel cell stack(s), air 
processing system, fuel flow control system, exhaust system, thermal 
management system, and water management system.
    High voltage live part means a live part of a high voltage source.
    High voltage source means any electric component which is contained 
in the electric power train or conductively connected to the electric 
power train and has a working voltage greater than 30 VAC or 60 VDC.
    Indirect contact is the contact of any person or persons with 
exposed conductive parts.
    Live part is a conductive part of the vehicle that is electrically 
energized under normal vehicle operation.
    Luggage compartment is the space in the vehicle for luggage 
accommodation, separated from the passenger compartment by the front or 
rear bulkhead and bounded by a roof, hood or trunk lid, floor, and side 
walls, as well as by electrical protection barriers provided for 
protecting the occupants from direct contact with high voltage live 
parts.
    Normal vehicle operation includes operating modes and conditions 
that can reasonably be encountered during typical operation of the 
vehicle, such as driving, parking, and standing in traffic, as well as 
charging using chargers that are compatible with the specific charging 
ports installed on the vehicle. It does not include conditions where 
the vehicle is damaged, either by a crash or road debris, subjected to 
fire or water submersion, or in a state where service and/or 
maintenance is needed or being performed.
    Parking mode is 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.
    Passenger compartment is the space for occupant accommodation that 
is bounded by the roof, floor, side walls, doors, outside glazing, 
front bulkhead and rear bulkhead or rear gate, as well as electrical 
protection barriers provided for protecting the occupants from direct 
contact with high voltage live parts.
    Propulsion system means an assembly of electric or electro-
mechanical components or circuits that propel the vehicle using the 
energy that is supplied by a high voltage source. This includes, but is 
not limited to, electric motors, inverters/converters, and electronic 
controllers.
    Protection degree IPXXB is protection from contact with high 
voltage live parts. It is tested by probing electrical protection 
barriers with the jointed test finger probe, IPXXB, in figure 7b to 
this standard.
    Protection degree IPXXD is protection from contact with high 
voltage live parts. It is tested by probing electrical protection 
barriers with the test wire probe, IPXXD, in figure 7a to this 
standard.
    Rechargeable Electrical Energy Storage System (REESS) means the 
rechargeable electric energy storage system that provides electric 
energy for electrical propulsion.
    Rupture means an opening through the casing of the REESS that would 
permit the IPXXB test probe to penetrate and contact live parts.
    Service disconnect is the device for deactivation of an electrical 
circuit when conducting checks and services of the vehicle electrical 
propulsion system.
    State of charge (SOC) means the available electrical charge in a 
REESS expressed as a percentage of the normal operating capacity 
specified by the vehicle manufacturer.
    Thermal event means the condition when the temperature within the 
REESS is significantly higher than the maximum operating temperature.
    Thermal runaway means an uncontrolled increase of cell temperature 
caused by exothermic reactions inside the cell.
    Thermal propagation means the sequential occurrence of thermal 
runaway within a REESS triggered by thermal runaway of a cell in the 
REESS.
    VAC means volts of alternating current (AC) expressed using the 
root mean square value.
    VDC means volts of direct current (DC).
    Vehicle charge inlet is the device on the electric vehicle into 
which the charge connector is inserted for the purpose of transferring 
energy and exchanging information from an external electric power 
supply.

[[Page 104354]]

    Venting means the release of excessive internal pressure from cell 
or battery in a manner intended by design to preclude rupture or 
explosion.
    Working voltage means the highest root mean square voltage of the 
voltage source, which may occur across its terminals or between its 
terminals and any conductive parts in open circuit conditions or under 
normal operating conditions.
    S5. General requirements.
    S5.1 Vehicles of GVWR of 4,536 kilograms (kg) or less (light 
vehicles). Each vehicle with a GVWR of 4,536 kg or less shall meet the 
requirements set forth in S6 (normal vehicle operation safety), S8 
(post-crash safety), S11 (vehicle controls managing REESS safe 
operations), S13 (warning in the case of thermal event in REESS), and 
S14 (water exposure safety) of this standard.
    S5.2 Vehicles with a GVWR greater than 4,536 kg other than school 
buses (heavy vehicles other than school buses). Each heavy vehicle with 
a GVWR greater than 4,536 kg, other than school buses, shall meet the 
requirements set forth in S6 (normal vehicle operation safety), S11 
(vehicle controls managing REESS safe operations), S13 (warning in the 
case of thermal event in REESS), and S14 (water exposure safety) of 
this standard.
    S5.3 School buses with a GVWR greater than 4,536 kg. Each school 
bus with a GVWR greater than 4,536 kg shall meet the requirements set 
forth in S6 (normal vehicle operation safety), S8 (post-crash safety), 
S11 (vehicle controls managing REESS safe operations), S13 (warning in 
the case of thermal event in REESS), and S14 (water exposure safety) of 
this standard.
    S6. Normal vehicle operation safety. Each vehicle to which this 
standard applies must meet the requirements in S6.1 to S6.6 of this 
standard, when tested according to the relevant provisions in S7 of 
this standard.
    S6.1 Protection against direct contact.
    S6.1.1 Marking. The symbol shown in figure 6 to this standard shall 
be present on or near electric energy storage devices. The symbol in 
figure 6 shall also be visible on electrical protection barriers which, 
when removed, expose live parts of high voltage sources. The symbol 
shall be yellow and the bordering and the arrow shall be black.
    S6.1.1.1 The marking is not required for electrical protection 
barriers that cannot be physically accessed, opened, or removed without 
the use of tools. Markings are not required for electrical connectors 
or the vehicle charge inlet.
    S6.1.2 High voltage cables. Cables for high voltage sources which 
are not located within electrical protection barriers shall be 
identified by having an outer covering with the color orange.
    S6.1.3 Service disconnect. For a service disconnect which can be 
opened, disassembled, or removed without tools, protection degree IPXXB 
shall be provided when tested under procedures specified in S7.3.1 of 
this standard using the IPXXB test probe shown in figures 7a and 7b to 
this standard.
    S6.1.4 Protection degree of high voltage live parts. (a) Protection 
degree IPXXD shall be provided for high voltage live parts inside the 
passenger or luggage compartment when tested according to the 
procedures specified in S7.3.1 of this standard using the IPXXD test 
probe shown in figure 7a to this standard.
    (b) Protection degree IPXXB shall be provided for high voltage live 
parts in areas other than the passenger or luggage compartment when 
tested according to the procedures specified in S7.3.1 of this standard 
using the IPXXB test probe shown in figures 7a and 7b to this standard. 
High voltage live parts that are not energized except during charging 
of the REESS are excluded from protection degree IPXXB if they are 
located on the vehicle roof such that the wrap around 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.
    S6.1.5 Connectors. All connectors shall provide direct contact 
protection by:
    (a) Meeting the requirements specified in S6.1.4 when the connector 
is connected to its corresponding mating component; and,
    (b) If a connector can be separated from its mating component 
without the use of a tool, meeting at least one of the following 
conditions from S6.1.5(b)(1), (2), or (3):
    (1) The connector meets the requirements of S6.1.4 when separated 
from its mating component;
    (2) The voltage of the live parts becomes less than or equal to 60 
VDC or 30 VAC within one second after the connector is separated from 
its mating component; or
    (3) The connector requires at least two distinct actions to 
separate from its mating component and there are other components that 
must be removed in order to separate the connector from its mating 
component and these other components cannot be removed without the use 
of tools.
    S6.1.6 Vehicle charge inlet. Direct contact protection for a 
vehicle charge inlet shall be provided by meeting the requirements 
specified in S6.1.4 when the charge connector is connected to the 
vehicle inlet and by meeting at least one of the requirements of 
S6.1.6(a) or (b).
    (a) The vehicle charge inlet meets the requirements of S6.1.4 when 
the charge connector is not connected to it; or
    (b) The voltage of the high voltage live parts becomes equal to or 
less than 60 VDC or equal to or less than 30 VAC within 1 second after 
the charge connector is separated from the vehicle charge inlet.
    S6.2 Protection against indirect contact.
    S6.2.1 The resistance between all exposed conductive parts of 
electrical protection barriers and the electrical chassis shall be less 
than 0.1 ohms when tested according to the procedures specified in 
S7.3.2 of this standard.
    S6.2.2 The resistance between any two simultaneously reachable 
exposed conductive parts of the electrical protection barriers that are 
less than 2.5 meters from each other shall be less than 0.2 ohms when 
tested according to the procedures specified in S7.3.2 of this 
standard.
    S6.3 Electrical isolation.
    S6.3.1 Electrical isolation of AC and DC high voltage sources. The 
electrical isolation of a high voltage source, determined in accordance 
with the procedure specified in S7.2 of this standard, must be greater 
than or equal to one of the following:
    (a) 500 ohms/volt for an AC high voltage source;
    (b) 100 ohms/volt for an AC high voltage source if it is 
conductively connected to a DC high voltage source, but only if the AC 
high voltage source meets the requirements for protection against 
direct contact in S6.1.4 and the protection from indirect contact in 
S6.2; or
    (c) 100 ohms/volt for a DC high voltage source.
    S6.3.2 Exclusion of high voltage sources from electrical isolation 
requirements. A high voltage source that is conductively connected to 
an electric component which is conductively connected to the electrical 
chassis and has a working voltage less than or equal to 60 VDC, 
including a pulsating DC voltage source without a change in polarity, 
is not required to meet the electrical isolation requirements in S6.3.1 
if the voltage between the high voltage source and the electrical 
chassis is less than or equal to 30 VAC or 60 VDC.
    S6.3.3 Electrical isolation of high voltage sources for charging 
the electric

[[Page 104355]]

energy storage device. For the vehicle charge inlet intended to be 
conductively connected to the AC external electric power supply, the 
electric isolation between the electrical chassis and the high voltage 
sources that are conductively connected to the vehicle charge inlet 
during charging of the electric energy storage device shall be greater 
than or equal to 500 ohms/volt when the charge connector is 
disconnected. The electrical isolation is measured at the high voltage 
live parts of the vehicle charge inlet and determined in accordance 
with the procedure specified in S7.2 of this standard. During the 
measurement, the electric energy storage device may be disconnected.
    S6.4 Electrical isolation monitoring. DC high voltage sources of 
vehicles with a fuel cell system shall be monitored by an electrical 
isolation monitoring system that displays a warning for loss of 
isolation when tested according to S7.4 of this standard. The system 
must monitor its own readiness and the visual warning display must be 
provided to the driver. For a vehicle with automated driving systems 
and without manually operated driving controls, the visual warning must 
be provided to all the front row occupants.
    S6.5 Electric shock protection during charging. For motor vehicles 
with an electric energy storage device that can be charged through a 
conductive connection with a grounded external electric power supply, a 
device to enable conductive connection of the electrical chassis to the 
earth ground shall be provided. This device shall enable connection to 
the earth ground before exterior voltage is applied to the vehicle and 
retain the connection until after the exterior voltage is removed from 
the vehicle.
    S6.6 Mitigating driver error.
    S6.6.1 Indicator of active driving possible mode. At least a 
momentary indication shall be given to the driver each time the vehicle 
is first placed in active driving possible mode after manual activation 
of the propulsion system. This requirement does not apply under 
conditions where an internal combustion engine directly or indirectly 
provides the vehicle's propulsion power when the vehicle is first 
placed in the active driving possible mode after manual activation of 
the propulsion system.
    S6.6.2 Indicator of active driving possible mode when leaving the 
vehicle. When leaving the vehicle, the driver shall be informed by an 
auditory or visual signal if the vehicle is still in the active driving 
possible mode.
    S6.6.3 Prevent drive-away. If the on-board electric energy storage 
device can be externally charged, vehicle movement of more than 150 mm 
by its own propulsion system shall not be possible as long as the 
charge connector of the external electric power supply is physically 
connected to the vehicle charge inlet in a manner that would permit 
charging of the electric energy storage device.
    S7. Electrical safety test procedures for normal vehicle operation 
safety. The following provisions specify the test procedures associated 
with the requirements of S6 of this standard.
    S7.1 Voltage measurements. For the purpose of determining the 
voltage level of the high voltage source, voltage is measured as shown 
in figure 1 to this standard using a voltmeter that has an internal 
resistance of at least 10 M[Omega]. All post-crash voltage measurements 
for determining electrical isolation of high voltage sources specified 
in S8.2(a) of this standard are made at least 10 seconds after impact. 
All post-crash voltage measurements for determining the voltage levels 
specified in S8.2(b) of this standard and the energy in capacitors 
specified in S8.2(d) of this standard are made between 10 to 60 seconds 
after impact.
    S7.1.1 For a high voltage source that has an automatic disconnect 
that is physically contained within itself, the voltage measurement 
after the test is made from the side of the automatic disconnect 
connected to the electric power train or to the rest of the electric 
power train if the high voltage source is a component contained in the 
power train. For a high voltage source that has an automatic disconnect 
that is not physically contained within itself, the voltage measurement 
after the test is made from both the high voltage source side of the 
automatic disconnect and from the side of the automatic disconnect 
connected to the electric power train or to the rest of the electric 
power train if the high voltage source is a component contained in the 
power train.
    S7.1.2 Voltage Vb is measured across the two terminals of the 
voltage source. Before a vehicle crash test, Vb is equal to or greater 
than the working voltage as specified by the vehicle manufacturer.
    S7.1.3 Voltage V1 is measured between the negative side of the high 
voltage source and the electrical chassis as shown in figure 2 to this 
standard. Voltage V2 is measured between the positive side of the high 
voltage source and the electrical chassis as shown in figure 3 to this 
standard.
    S7.2 Test method for determining electrical isolation. Measure the 
voltages V1, V2, and Vb as shown in figure 1 to this standard in 
accordance with S7.1.
    S7.2.1 If V1 is greater than or equal to V2, insert a known 
resistance (Ro) between the negative side of the high voltage source 
and the electrical chassis. With the Ro installed, measure the voltage 
(V1') as shown in figure 4 to this standard between the negative side 
of the high voltage source and the electrical chassis. Calculate the 
electrical isolation resistance (Ri) according to the formula shown. 
Divide Ri (in ohms) by the working voltage of the high voltage source 
(in volts) to obtain the electrical isolation (in ohms/volt).
    S7.2.2 If V2 is greater than V1, insert a known resistance (Ro) 
between the positive side of the high voltage source and the electrical 
chassis. With the Ro installed, measure the voltage (V2') as shown in 
figure 5 to this standard between the positive side of the high voltage 
source and the electrical chassis. Calculate the electrical isolation 
resistance (Ri) according to the formula shown. Divide Ri (in ohms) by 
the working voltage of the high voltage source (in volts) to obtain the 
electrical isolation (in ohms/volt).
    S7.3 Test methods for evaluating physical barrier protection.
    S7.3.1 Test method to evaluate protection from direct contact with 
high voltage sources. (a) Any parts surrounding the high voltage 
components are opened, disassembled, or removed without the use of 
tools.
    (b) The selected access probe is inserted into any gaps or openings 
of the electrical protection barrier with a test force between 9 Newton 
to 11 Newton with the IPXXB probe or 1 Newton to 2 Newton with the 
IPXXD probe. If the probe partly or fully penetrates into the 
electrical protection barrier, it is placed in every possible position 
to evaluate contact with high voltage live parts. If partial or full 
penetration into the electrical protection barrier occurs with the 
IPXXB probe, the IPXXB probe shall be placed as follows: starting from 
the straight position, both joints of the test finger are rotated 
progressively through an angle of up to 90 degrees with respect to the 
axis of the adjoining section of the test finger and are placed in 
every possible position.
    (c) A low voltage supply (of not less than 40 V and not more than 
50 V) in series with a suitable lamp may be connected between the 
access probe and any high voltage live parts inside the electrical 
protection barrier to indicate whether high voltage live parts were 
contacted.

[[Page 104356]]

    (d) A mirror or fiberscope may be used to inspect whether the 
access probe touches high voltage live parts inside the electrical 
protection barrier.
    (e) Protection degree IPXXD or IPXXB is verified when the following 
conditions are met:
    (1) The access probe does not touch high voltage live parts. The 
IPXXB access probe may be manipulated as specified in S7.3.1(b) for 
evaluating contact with high voltage live parts. The methods specified 
in S7.3.1(c) or S7.3.1(d) may be used to aid the evaluation. If method 
S7.3.1(c) is used for verifying protection degree IPXXB or IPXXD, the 
lamp shall not light up.
    (2) The stop face of the access probe does not fully penetrate into 
the electrical protection barrier.
    S7.3.2 Test method to evaluate protection against indirect contact 
with high voltage sources. Any parts surrounding the high voltage 
components are opened, disassembled, or removed without the use of 
tools. At the option of the manufacturer, protection against indirect 
contact with high voltage sources shall be determined using the test 
method in S7.3.2(a) or (b).
    (a) Test method using a resistance tester. The resistance tester is 
connected to the measuring points (the electrical chassis and any 
exposed conductive part of electrical protection barriers or any two 
simultaneously reachable exposed conductive parts of electrical 
protection barriers that are less than 2.5 meters from each other), and 
the resistance is measured using a resistance tester that can supply 
current levels of at least 0.2 Amperes with a resolution of 0.01 ohms 
or less. The resistance between two exposed conductive parts of 
electrical protection barriers that are less than 2.5 meters from each 
other may be calculated using the separately measured resistances of 
the relevant parts of the electric path.
    (b) Test method using a DC power supply, voltmeter, and ammeter. 
(1) Connect the DC power supply, voltmeter, and ammeter to the 
measuring points (the electrical chassis and any exposed conductive 
part or any two simultaneously reachable exposed conductive parts that 
are less than 2.5 meters from each other) as shown in figure 8 to this 
standard.
    (2) Adjust the voltage of the DC power supply so that the current 
flow becomes more than 0.2 Amperes.
    (3) Measure the current I and the voltage V shown in figure 8 to 
this standard.
    (4) Calculate the resistance R according to the formula, R = V/I.
    (5) The resistance between two simultaneously reachable exposed 
conductive parts of electrical protection barriers that are less than 
2.5 meters from each other may be calculated using the separately 
measured resistances of the relevant parts of the electric path.
    S7.3.3 Test method to determine voltage between exposed conductive 
parts of electrical protection barriers and the electrical chassis and 
between exposed conductive parts of electrical protection barriers. (a) 
Any parts surrounding the high voltage components are opened, 
disassembled, or removed without the use of tools.
    (b) Connect the voltmeter to the measuring points (exposed 
conductive part of an electrical protection barrier and the electrical 
chassis or any two simultaneously reachable exposed conductive parts of 
electrical protection barriers that are less than 2.5 meters from each 
other).
    (c) Measure the voltage.
    (d) The voltage between two simultaneously reachable exposed 
conductive parts of electrical protection barriers that are less than 
2.5 meters from each other may be calculated using the separately 
measured voltages between the relevant electrical protection barriers 
and the electrical chassis.
    S7.4 Test method for evaluating on-board electrical isolation 
monitoring system. Prior to any impact test, the requirements of S6.4 
of this standard for the on-board electrical isolation monitoring 
system shall be tested using the following procedure.
    (a) The electric energy storage device is at the state of charge 
specified in S7.1.
    (b) The switch or device that provides power from the electric 
energy storage/conversion system to the propulsion system is in the 
activated position or the ready-to-drive position.
    (c) Determine the isolation resistance, Ri, of the high voltage 
source with the electrical isolation monitoring system using the 
procedure outlined in S7.2.
    (d) Insert a resistor with resistance Ro equal to or greater than 
1/(1/(95 times the working voltage of the high voltage source)-1/Ri) 
and less than 1/(1/(100 times the working voltage of the high voltage 
source)-1/Ri) between the positive terminal of the high voltage source 
and the electrical chassis.
    (e) The electrical isolation monitoring system indicator shall 
provide a visual warning to the driver. For a vehicle with automated 
driving systems and without manually operated driving controls, the 
visual warning must be provided to all the front row occupants.
    S7.5 Test method for determining post-crash energy in capacitors. 
(a) Prior to the crash tests, the vehicle manufacturer must identify 
the capacitors, type of capacitors (x-capacitors and y-capacitors) and 
their respective capacitance (Cx and Cy1 and Cy2) 
in the electric power train for which the low energy compliance option 
for post-crash electrical safety in S8.2(d) of this standard is 
applied.
    (b) Voltages Vb, V1, and V2 are measured across the capacitors in 
accordance with S7.1.
    (c) The total energy in a x-capacitor is equal to 0.5 x Cx x Vb\2\.
    (d) The total energy in the y-capacitor Cy1 is equal to 
0.5 x Cy1 x V1\2\ and the total energy in the y-capacitor 
Cy2 is equal to 0.5 x Cy2 x V2\2\.
    S8. Post-crash safety. Each vehicle with a GVWR of 4,536 kg or less 
to which this standard applies must meet the requirements in S8.1, 
S8.2, S8.3, and S8.4 when tested according to S9 of this standard under 
the conditions of S10 of this standard. Each school bus with a GVWR 
greater than 4,536 kg to which this standard applies must meet the 
requirements in S8.1, S8.2, S8.3, and S8.4 when tested according to 
S9.5 of this standard under the conditions of S10.
    S8.1 Fire safety. Starting from the time of impact and continuing 
until one hour after the completion of the sequence of tests specified 
in S9 of this standard, there shall be no evidence of fire or explosion 
in any part of the vehicle. The assessment of fire or explosion is 
verified by visual inspection without disassembly of the REESS or 
vehicle.
    S8.2 Electrical safety. After each test specified in S9 of this 
standard, each high voltage source in a vehicle must meet one of the 
following electrical safety requirements: electrical isolation 
requirements of S8.2(a), the voltage level requirements of S8.2 (b), or 
the physical barrier protection requirements of S8.2(c); or the high 
voltage capacitors in the electric power train must meet the low-energy 
requirements of S8.2(d).
    (a) The electrical isolation of the high voltage source, determined 
in accordance with the procedure specified in S7.2 of this standard, 
must be greater than or equal to one of the following:
    (1) 500 ohms/volt for an AC high voltage source;
    (2) 100 ohms/volt for an AC high voltage source if it is 
conductively connected to a DC high voltage source, but only if the AC 
high voltage source meets the physical barrier protection requirements 
specified in S8.2(c)(1) and (2); or
    (3) 100 ohms/volt for a DC high voltage source.

[[Page 104357]]

    (b) The voltages V1, V2, and Vb of the high voltage source, 
measured according to the procedure specified in S7.1 of this standard, 
must be less than or equal to 30 VAC for AC components or 60 VDC for DC 
components.
    (c) Protection against electric shock by direct and indirect 
contact (physical barrier protection) shall be demonstrated by meeting 
the following three conditions:
    (1) The high voltage source (AC or DC) meets the protection degree 
IPXXB when tested according to the procedure specified in S7.3.1 of 
this standard using the IPXXB test probe shown in figures 7a and 7b to 
this standard;
    (2) The resistance between exposed conductive parts of the 
electrical protection barrier of the high voltage source and the 
electrical chassis is less than 0.1 ohms when tested according to the 
procedures specified in S7.3.2 of this standard. In addition, the 
resistance between an exposed conductive part of the electrical 
protection barrier of the high voltage source and any other 
simultaneously reachable exposed conductive parts of electrical 
protection barriers within 2.5 meters of it must be less than 0.2 ohms 
when tested using the test procedures specified in S7.3.2 of this 
standard; and
    (3) The voltage between exposed conductive parts of the electrical 
protection barrier of the high voltage source and the electrical 
chassis is less than or equal to 30 VAC or 60 VDC as measured in 
accordance with S7.3.3 of this standard. In addition, the voltage 
between an exposed conductive part of the electrical protection barrier 
of the high voltage source and any other simultaneously reachable 
exposed conductive parts of electrical protection barriers within 2.5 
meters of it must be less than or equal to 30 VAC or 60 VDC as measured 
in accordance with S7.3.3 of this standard.
    (d) The total energy of unidirectional single impulse currents from 
capacitors shall be less than 0.2 Joules when determined in accordance 
with the procedure specified in S7.5 of this standard.
    S8.3 Electric energy storage/conversion device retention. During 
and after each test specified in S9 of this standard:
    (a) Electric energy storage/conversion devices shall remain 
attached to the vehicle by at least one component anchorage, bracket, 
or any structure that transfers loads from the device to the vehicle 
structure, and
    (b) Electric energy storage/conversion devices located outside the 
occupant compartment shall not enter the occupant compartment.
    S8.4 Electrolyte leakage from electric energy storage devices. Not 
more than 5.0 liters of electrolyte shall leak from electric energy 
storage devices, and no visible trace of electrolyte shall leak into 
the passenger compartment. Leakage is measured from the time of the 
impact until 30 minutes thereafter, and throughout any static rollover 
after a barrier impact test, specified in S9 of this standard.
    S9. Crash test specifications. A test vehicle with a GVWR less than 
or equal to 4,536 kg, under the conditions of S10 of this standard, is 
subject to any one single barrier crash test of S9.1, S9.2, or S9.3, 
followed by the static rollover test of S9.4. A school bus with a GVWR 
greater than 4,536 kg, under the conditions of S10, is subject to the 
contoured barrier crash test of S9.5. A particular vehicle need not 
meet further test requirements after having been subjected to a single 
barrier crash/static rollover test sequence.
    S9.1 Frontal barrier crash. The test vehicle, with test dummies in 
accordance with S6.1 of Sec.  571.301, traveling longitudinally forward 
at any speed up to and including 48 km/h, impacts a fixed collision 
barrier that is perpendicular to the line of travel of the vehicle, or 
at an angle up to 30 degrees in either direction from the perpendicular 
to the line of travel of the vehicle.
    S9.2 Rear moving barrier impact. The test vehicle, with test 
dummies in accordance with S6.1 of Sec.  571.301, is impacted from the 
rear by a barrier that conforms to S7.3(b) of Sec.  571.301 and that is 
moving at any speed between 79 and 81 km/h.
    S9.3 Side moving deformable barrier impact. The test vehicle, with 
the appropriate 49 CFR part 572 test dummies specified in Sec.  571.214 
at positions required for testing by S7.1.1, S7.2.1, or S7.2.2 of 
Standard 214 (Sec.  571.214), is impacted laterally on either side by a 
moving deformable barrier moving at any speed between 52.0 km/h and 
54.0 km/h.
    S9.4 Post-impact test static rollover. After each crash test 
specified in S9.1, S9.2, and S9.3, without any alteration of the 
vehicle, the vehicle is rotated on its longitudinal axis to each 
successive increment of 90 degrees under the test conditions of S10.3 
of this standard.
    S9.5 Moving contoured barrier crash. The test vehicle, under the 
conditions of S10.1 and S10.2 of this standard, is impacted at any 
point and at any angle by the moving contoured barrier assembly, 
specified in S7.5 and S7.6 in Sec.  571.301, traveling longitudinally 
forward at any speed up to and including 48 km/h.
    S10. Crash test conditions.
    S10.1 State of charge. The electric energy storage device(s) shall 
be at the state of charge specified in either S10.1(a), (b), or (c):
    (a) At the maximum state of charge in accordance with the vehicle 
manufacturer's recommended charging procedures, as stated in the 
vehicle owner's manual or on a label that is permanently affixed to the 
vehicle; or
    (b) If the manufacturer has made no recommendation for charging 
procedures in the owner's manual or on a label permanently affixed to 
the vehicle, at a state of charge of not less than 95 percent of the 
maximum capacity of the electric energy storage device(s); or
    (c) If the electric energy storage device(s) is/are rechargeable 
only by an energy source on the vehicle, at any state of charge within 
the normal operating voltage defined by the vehicle manufacturer.
    S10.2 Vehicle conditions. The switch or device that provides power 
from the electric energy storage/conversion system to the propulsion 
system is in the activated position or the ready-to-drive position. 
Bypass any devices or systems that do not allow the propulsion system 
to be energized at the time of impact when the vehicle ignition is on 
and the vehicle is in neutral.
    S10.2.1 The parking brake is disengaged and the vehicle drive 
system is in the neutral position. In a test conducted under S9.3 of 
this standard, the parking brake is set.
    S10.2.2 Tires are inflated to the manufacturer's specifications.
    S10.2.3 The vehicle, including test devices and instrumentation, is 
loaded as follows:
    (a) A passenger car is loaded to its unloaded vehicle weight plus 
its rated cargo and luggage capacity weight, secured in the luggage 
compartment, plus the necessary test dummies as specified in S9 of this 
standard, restrained only by means that are installed in the vehicle 
for protection at its seating position.
    (b) A multipurpose passenger vehicle, truck, or bus, with a GVWR of 
4,536 kg (10,000 lb) or less, is loaded to its unloaded vehicle weight 
plus the necessary dummies, as specified in S9 of this standard, plus 
136 kg or its rated GVWR, whichever is less, secured in the load 
carrying area and distributed as nearly as possible in proportion to 
its GVWR. For the purpose of this standard, unloaded vehicle weight 
does not include the weight of work-performing accessories. Each dummy 
is restrained only by means that are installed in the

[[Page 104358]]

vehicle for protection at its seating position.
    (c) A school bus with a GVWR greater than 4,536 kg is loaded to its 
unloaded vehicle weight, plus 54 kg of unsecured mass at each 
designated seating position.
    S10.3 Static rollover test conditions. The vehicle is rotated about 
its longitudinal axis, with the axis kept horizontal, to each 
successive increment of 90[deg], 180[deg], and 270[deg] at a uniform 
rate, with 90[deg] of rotation taking place in any time interval from 1 
to 3 minutes. After reaching each 90[deg] increment the vehicle is held 
in that position for 5 minutes.
    S10.4 Rear moving barrier impact test conditions. The conditions of 
S7.3(b) and S7.6 of Sec.  571.301 apply to the conducting of the rear 
moving deformable barrier impact test specified in S9.2 of this 
standard.
    S10.5 Side moving deformable barrier impact test conditions. The 
conditions of S8.9, S8.10, and S8.11 of Sec.  571.214 apply to the 
conduct of the side moving deformable barrier impact test specified in 
S9.3 of this standard.
    S11. Vehicle controls managing REESS safe operations. Each vehicle 
to which the standard applies shall meet the requirements in S11.1, 
when tested according to S12 of this standard and the requirements in 
S11.2.
    S11.1 When tested in accordance with the overcharge test in S12.1, 
the over-discharge test in S12.2, the overcurrent test in S12.3, the 
high-temperature test in S12.4, and the short circuit test in 
accordance with S12.5 of this standard, each vehicle shall meet the 
following:
    (a) During the test, there shall be no evidence of electrolyte 
leakage, rupture, venting, fire, or explosion of the REESS as verified 
by visual inspection without disassembly of the vehicle.
    (b) The isolation resistance of the high voltage sources measured 
after the test shall not be less than 100 ohms/volt when determined in 
accordance with S7.2 of this standard.
    S11.2 In the event of operational failure of the vehicle controls 
that manage safe operation of the REESS, the vehicle must provide a 
visual warning while in active driving possible mode. The warning 
system shall monitor its own readiness and the visual warning must be 
provided to the driver. For a vehicle with automated driving systems 
and without manually operated driving controls, the visual warning must 
be provided to all the front row occupants.
    S12. Test methods for evaluating vehicle controls managing REESS 
safe operations.
    S12.1 Overcharge test. The overcharge test is conducted at ambient 
temperatures between 10 [deg]C and 30 [deg]C, with the vehicle REESS 
initially set between 90 to 95 percent SOC. The following steps are 
conducted to evaluate the vehicle's overcharge protection controls:
    (a) A breakout harness is connected to the traction side of the 
REESS. The manufacturer must specify an appropriate location(s) and 
attachment point(s) to connect the breakout harness.
    (b) Temperature probes are connected to the REESS outer casing to 
monitor changes in REESS temperature. Temperature measurements may also 
be obtained through communication with the REESS control module.
    (c) The external charge/discharge equipment, with maximum voltage 
and current set at least 10 percent higher than the REESS voltage and 
current limits, is connected to the breakout harness.
    (d) The vehicle switch or device that provides power to the vehicle 
controls that manage REESS operations is set to the activated position.
    (e) The REESS is charged with the external charge/discharge 
equipment with the maximum charge current specified by the 
manufacturer. If the manufacturer does not specify an appropriate 
charge current, then a charge rate of \1/3\C is used.
    (f) Charging is continued until one of the following occurs:
    (1) The overcharge protection control terminates the charge 
current;
    (2) The REESS temperature is 10 [deg]C above the manufacturer-
specified maximum operating temperature of the REESS; or
    (3) 12 hours have passed since the start of charging the vehicle.
    (g) After the charge current is terminated, if charge and discharge 
are permitted by the vehicle controls, a standard cycle is performed in 
accordance with S12.6.
    (h) After the completion of the standard cycle, or if the standard 
cycle was not performed, after charging is terminated, the vehicle is 
observed for 1 hour for evidence of electrolyte leakage, rupture, 
venting, fire, or explosion of the REESS.
    (i) At the conclusion of the test, electrical isolation of the 
REESS is determined in accordance with S7.2 of this standard.
    S12.2 Over-discharge test. The over-discharge test is conducted at 
ambient temperatures between 10 [deg]C and 30 [deg]C, with the vehicle 
REESS initially set between 10 and 15 percent SOC. For a vehicle with 
on-board energy conversion systems such as an internal combustion 
engine or a fuel cell, the fuel supply is set to the minimum level 
where active driving possible mode is permitted. The following steps 
are conducted to evaluate the vehicle's over-discharge protection 
controls:
    (a) A breakout harness is connected to the traction side of the 
REESS. The manufacturer must specify an appropriate location(s) and 
attachment point(s) to connect the breakout harness.
    (b) Temperature probes are connected to the REESS outer casing to 
monitor changes in REESS temperature. Temperature measurements may also 
be obtained through communication with the REESS control module.
    (c) The external charge/discharge equipment, with maximum voltage 
and current set at least 10 percent higher than the REESS voltage and 
current limits, is connected to the breakout harness.
    (d) The vehicle switch or device that provides power from the REESS 
to the electric power train is set to the activated position or the 
active driving possible mode.
    (e) The REESS is discharged with the external charge/discharge 
equipment with the maximum discharge rate under normal operating 
conditions specified by the manufacturer. If the manufacturer does not 
specify an appropriate discharge rate, a power load of 1kW is used.
    (f) Discharging is continued until one of the following occurs:
    (1) The over-discharge protection control terminates the discharge 
current;
    (2) The temperature gradient of the REESS is less than 4[deg]C 
through 2 hours from the start of discharge; or
    (3) The vehicle is discharged to 25 percent of its working voltage 
level.
    (g) After the discharge current is terminated, a standard cycle is 
performed in accordance with S12.6, if charge and discharge are 
permitted by the vehicle controls.
    (h) After the completion of the standard cycle, or if the standard 
cycle was not performed, after discharging is terminated, the vehicle 
is observed for 1 hour for evidence of electrolyte leakage, rupture, 
venting, fire, or explosion of the REESS.
    (i) At the conclusion of the test, electrical isolation of the 
REESS is determined in accordance with S7.2 of this standard.
    S12.3 Overcurrent test. The overcurrent test is only conducted on 
vehicles that have the capability of charging by DC external 
electricity supply. The test is conducted at ambient temperatures 
between 10 [deg]C and 30 [deg]C, with the vehicle REESS initially set 
between 40 to 50 percent SOC. The following steps are conducted to

[[Page 104359]]

evaluate the vehicle's over-current protection controls:
    (a) A breakout harness is connected to the traction side of the 
REESS. The manufacturer must specify an appropriate location(s) and 
attachment point(s) to connect the breakout harness.
    (b) Temperature probes are connected to the REESS outer casing to 
monitor changes in REESS temperature. Temperature measurements may also 
be obtained through communication with the REESS control module.
    (c) The external charge/discharge equipment, with maximum voltage 
and current set at least 10 percent higher than the REESS voltage and 
current limits, is connected to the breakout harness.
    (d) The vehicle switch or device that provides power to the vehicle 
controls that manage REESS operations is set to the activated position.
    (e) The REESS is charged with the external charge/discharge 
equipment with the maximum charge current specified by the 
manufacturer. If the manufacturer does not specify an appropriate 
charge current, then a charge rate of \1/3\C is used.
    (f) After charging is initiated, the overcurrent specified by the 
manufacturer is supplied over the course of 5 seconds from the maximum 
charge current level to the over-current level. If the vehicle 
manufacturer does not supply an overcurrent level, a 10 Ampere over-
current is supplied over 5 seconds. If charging is not terminated, the 
over-current supply is increased in steps of 10 Amperes.
    (g) Charging at the over-current level is continued until one of 
the following occurs:
    (1) The over-current protection control terminates the charge 
current; or
    (2) The temperature gradient of the REESS is less than 4 [deg]C 
through 2 hours from the first overcurrent input.
    (h) After the charge current is terminated, if charge and discharge 
are permitted by the vehicle controls, a standard cycle is performed in 
accordance with S12.6.
    (i) After the completion of the standard cycle or if the standard 
cycle was not performed, after charging is terminated, the vehicle is 
observed for 1 hour for evidence of electrolyte leakage, rupture, 
venting, fire, or explosion of the REESS.
    (j) At the conclusion of the test, electrical isolation of the 
REESS is determined in accordance with S7.2 of this standard.
    S12.4 Over-temperature test. The overtemperature test is conducted 
at ambient temperatures between 10 [deg]C and 30 [deg]C on a chassis-
dynamometer with the vehicle REESS initially set between 90 to 95 
percent SOC. For a vehicle with on-board energy conversion systems such 
as an internal combustion engine or a fuel cell, the fuel supply is set 
to allow operation for about one hour of driving. The following steps 
are conducted to evaluate the vehicle's high temperature protection 
controls:
    (a) The cooling system of the REESS is disabled using manufacturer 
supplied information. For an REESS that will not operate if the cooling 
system is disabled, the cooling operation is significantly reduced. If 
manufacturer does not supply information to disable or significantly 
reduce the cooling system, methods such as crimping the liquid cooling 
hose, removing refrigerant fluid, or blocking cabin air intakes for air 
cooled REESS are applied.
    (b) Temperature probes are connected to the REESS outer casing to 
monitor changes in REESS temperature. Temperature measurements may also 
be obtained through communication with the REESS control module.
    (c) The vehicle is installed on a chassis dynamometer and the 
vehicle switch or device that provides power from the REESS to the 
electric power train is set to the activated position or the active 
driving possible mode.
    (d) The vehicle is driven on the dynamometer using an appropriate 
vehicle manufacturer supplied drive profile and charging information 
for discharge and charge of the REESS to raise the REESS temperature to 
its upper boundary safe operating temperature within one hour. If an 
appropriate manufacturer-supplied drive profile is not available, the 
vehicle is repeatedly accelerated to 80 mph and then decelerated to 15 
mph within 40 seconds. If the manufacturer does not supply a charge 
profile, then a charge rate greater than \1/3\C current is used.
    (e) The discharge/charge procedure on the chassis-dynamometer is 
continued until one of the following occurs:
    (1) The vehicle terminates the discharge/charge cycle;
    (2) The temperature gradient of the REESS is less than 4 [deg]C 
through 2 hours from the start of the discharge/charge cycle; or
    (3) Three (3) hours have passed since the start of discharge/charge 
cycles.
    (f) After the discharge and charge procedure is terminated, if 
charge and discharge are permitted by the vehicle controls, a standard 
cycle is performed in accordance with S12.6.
    (g) After the completion of the standard cycle, or if the standard 
cycle is not performed, after the discharge and charge procedure is 
terminated, the vehicle is observed for 1 hour for evidence of 
electrolyte leakage, rupture, venting, fire, or explosion of the REESS.
    (h) At the conclusion of the test, electrical isolation of the 
REESS is determined in accordance with S7.2 of this standard.
    S12.5 External short circuit test. The short circuit test is 
conducted at ambient conditions with the vehicle REESS initially set 
between 90 to 95 percent SOC. The following steps are conducted to 
evaluate the vehicle's external short circuit protection controls:
    (a) A breakout harness is connected to the REESS. The manufacturer 
must specify an appropriate location(s) and attachment point(s) to 
connect the breakout harness.
    (b) Temperature probes are connected to the REESS outer casing to 
monitor changes in REESS temperature. Temperature measurements may also 
be obtained through communication with the REESS control module.
    (c) The vehicle switch or device that provides power to the vehicle 
controls that manage REESS operations is set to the activated position.
    (d) The short circuit contactor (with the contactors in open 
position) is connected to the breakout harnesses. The total resistance 
of the equipment to create the external short circuit (short circuit 
contactor and breakout harnesses) is verified to be between 2 to 5 
milliohms.
    (e) The short circuit contactor is closed to initiate the short 
circuit.
    (f) The short circuit condition is continued until one of the 
following occurs:
    (1) Short circuit current is terminated; or
    (2) The temperature gradient of the REESS is less than 4 [deg]C 
through 2 hours from the start of initiating the short circuit 
condition.
    (g) After the short circuit current is terminated, if charge and 
discharge are permitted by the vehicle controls, a standard cycle is 
performed in accordance with S12.6.
    (h) After the completion of the standard cycle, or if the standard 
cycle was not performed, after short circuit current is terminated, the 
vehicle is observed for 1 hour for evidence of electrolyte leakage, 
rupture, venting, fire, or explosion of the REESS.
    (i) At the conclusion of the test, electrical isolation of the 
REESS is determined in accordance with S7.2 of this standard.
    S12.6 Standard cycle. The standard cycle is conducted at ambient 
temperatures between 10 [deg]C and 30 [deg]C and starts with a standard 
discharge

[[Page 104360]]

followed by a standard charge. The discharge and charge procedures 
would follow manufacturer supplied information. The charge procedure is 
initiated 15 minutes after discharge is terminated.
    (a) If the manufacturer does not provide a discharge procedure, the 
vehicle is discharged with 1C current until discharge is terminated by 
vehicle controls.
    (b) If the manufacturer does not provide a charge procedure, the 
vehicle is charged with \1/3\C current until terminated by vehicle 
controls.
    S13. Warning in the case of thermal event in REESS. The vehicle 
shall provide a warning to the driver in the case of a thermal event in 
the REESS when the vehicle is in active driving possible mode. The 
thermal event warning system must monitor its own readiness. The 
warning shall activate within three minutes of the onset of the thermal 
event. The warning shall consist of auditory and visual signals that 
remain active for at least 5 minutes. For a vehicle with automated 
driving systems and without manually operated driving controls, the 
visual warning must be provided to all the front row occupants.
    S14. Water exposure safety. Each vehicle to which the standard 
applies shall maintain electrical isolation as specified in S6.3.1 and 
S6.3.2 of this standard at these times:
    (a) Just after exposure to water in each of the two tests specified 
below and with the vehicle still wet; and
    (b) After a minimum of 24 hours after completing each of the tests 
specified in S14.1 and S14.2.
    S14.1 Vehicle washing test. The vehicle is sprayed from any 
direction with a stream of freshwater from a standard test nozzle shown 
in figure 9 to this standard that has a nozzle internal diameter of 6.3 
millimeters, delivery rate of 11.9 to 13.2 liters/minute, and water 
pressure at the nozzle between 30 kPa to 35 kPa.
    (a) During the washing, the distance from the nozzle to the vehicle 
surface is 3.0 to 3.2 meters. The distance of the nozzle from the 
vehicle surface may be reduced, if necessary, to ensure the surface is 
wet when spraying upwards. The washing test duration per square meter 
of the vehicle surface area is 60 to 75 seconds, with a minimum total 
test duration of 3 minutes.
    (b) The vehicle external surface, including the vehicle sides, 
front, rear, top, and bottom is exposed to the water stream. Border 
lines on the vehicle such glass seals, outline of opening parts (doors, 
windows, vehicle inlet cover), outline of front grille, and seals of 
vehicle lamps are exposed to the water stream from any direction.
    (c) At the conclusion of the normal washing test, with the vehicle 
still wet, electrical isolation is determined in accordance with S7.2 
of this standard.
    S14.2 Driving through standing water test. The vehicle is driven 
through a wade pool of at least 10 centimeters but not more than 15 
centimeters depth of freshwater for a distance of 500 meters at a 
minimum speed of 12 mph (20 km/h) but not more than 15 mph (24 km/h).
    (a) If the wade pool is less than 500 m in length, then the vehicle 
shall be driven through it several times for a total distance of 500 m. 
The total time, including the period outside of the wade pool, shall be 
less than 10 minutes.
    (b) At the conclusion of the standing water test, with the vehicle 
still wet, electrical isolation is determined in accordance with S7.2 
of this standard.

Figures to FMVSS No. 305a
[GRAPHIC] [TIFF OMITTED] TR20DE24.000

Figure 1. Voltage Measurements of the High Voltage Source

[[Page 104361]]

[GRAPHIC] [TIFF OMITTED] TR20DE24.001

Figure 2. Measurement for V1 Voltage Between the Negative Side of the 
High Voltage Source and the Electrical Chassis
[GRAPHIC] [TIFF OMITTED] TR20DE24.002

Figure 3. Measurement for V2 Voltage Between the Positive Side of the 
High Voltage Source and the Electrical Chassis

[[Page 104362]]

[GRAPHIC] [TIFF OMITTED] TR20DE24.003

Figure 4. Measurement for V1' Voltage Across Resistor Between Negative 
Side of the High Voltage Source and Electrical Chassis
[GRAPHIC] [TIFF OMITTED] TR20DE24.004


[[Page 104363]]



Figure 5. Measurement for V2' Voltage Across Resistor Between Positive 
Side of the High Voltage Source and Electrical Chassis
[GRAPHIC] [TIFF OMITTED] TR20DE24.005

Figure 6. Marking of High Voltage Sources
[GRAPHIC] [TIFF OMITTED] TR20DE24.006

Figure 7a. Access Probes for the Tests of Direct Contact Protection. 
Access Probe IPXXB (Top) and Access Probe IPXXD (Bottom)

[[Page 104364]]

[GRAPHIC] [TIFF OMITTED] TR20DE24.007

Figure 7b. Jointed Test Finger IPXXB

[[Page 104365]]

[GRAPHIC] [TIFF OMITTED] TR20DE24.008

Figure 8. Connection To Determine Resistance Between Exposed Conductive 
Parts of Electrical Protection Barrier and Electrical Chassis
[GRAPHIC] [TIFF OMITTED] TR20DE24.009

Figure 9. Standard Nozzle for IPX5 Water Exposure Test

    Issued in Washington, DC, under authority delegated in 49 CFR 
1.95 and 501.
Adam Raviv,
Chief Counsel.
[FR Doc. 2024-28707 Filed 12-19-24; 8:45 am]
BILLING CODE 4910-59-P`