The National Highway Traffic Safety Administration (NHTSA) has issued two notices of proposed rulemaking concerning electric- and hydrogen-powered vehicles.

Among other improvements, Federal Motor Vehicle Safety Standard (FMVSS) No. 305a would apply to light and heavy vehicles and would have performance and risk mitigation requirements for the propulsion battery.

Under the 2022 recommendation of the National Transportation Safety Board (NTSB), 22 automakers updated their Emergency Response Guides (ERGs) to include the safety risks of EV lithium-ion battery fires at crash scenes and how to properly put them out, including compliance with the International Organization for Standardization’s (ISO)’s Standard 17840: Road Vehicles — Information for First and Second Responders.

In an investigation, NTSB found two primary safety issues: inadequacy of vehicle manufacturers’ ERGs as well as gaps in safety standards and research related to high-voltage lithium-ion batteries when involved in high-speed and high-severity crashes.

Relating to the NTSB’s recommendation, NHTSA’s FMVSS No. 305a would require manufacturers to submit standardized emergency response information for each vehicle by make, model, and model year. The information would be published in an easily searchable and standardized format on NHTSA’s website to assist first and second responders who handle electric vehicles (EVs) exposed to fire or water submersion and that are towed and stored, the notice states.

ERGs also provide the location of EV components that could harm occupants or rescue personnel, specific information about the function or danger of the components, and devices or measures that inhibit a dangerous state.

Compliance would be two years after the date of publication of the final rule in the Federal Register. Small-volume manufacturers, final-stage manufacturers, and alterers would be given an additional year to comply.

If approved, the final rule would include all of NHTSA’s current FMVSS No. 305, but would expand on its applicability to vehicles with a gross vehicle weight rating greater than 10,000 pounds as well as add requirements and test procedures for new aspects of electric vehicle safety. The current rule only applies to light vehicles, which are under 10,000 pounds.

The proposed requirements include performance and risk mitigation requirements for the propulsion battery, referred to as the Rechargeable Electrical Energy Storage System (REESS). A REESS provides electric energy for propulsion and may include necessary ancillary systems for physical support, thermal management, electronic controls, and casings, according to the FMVSS.

NHTSA also aims to ensure first and second responders have access to vehicle-specific information about extinguishing REESS fires to mitigate safety risks associated with stranded energy when responding to emergencies, the notice states.

NHTSA says it will continue to upgrade the FMVSS as battery technologies and charging systems evolve.

The NPRM lays out post-crash requirements for light vehicles and heavy school buses as well, including:

• • Electric shock protection under four compliance options – low voltage, electrical isolation, protective barrier, and low energy for capacitors;
  • REESS retention;
  • Electrolyte leakage; and
  • Fire safety.

REESS retention and electrolyte leakage are already in the current federal standard but would 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,” the FMVSS states. “To account for the potential delayed response, NHTSA is proposing to prohibit fire or explosion for a one-hour post-test period.”

The proposal would require protection of the REESS against external fault inputs, REESS operation 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 under normal vehicle operations.

EV manufacturers would have to provide documentation to address:

• • Safety risk mitigation associated with charging and discharging during low temperatures;
  • Safety risks from thermal propagation in the event of single-cell thermal runaway (SCTR) due to an internal short-circuit of a single cell; and
  • A warning if there is a malfunction of vehicle controls that manage REESS safe operation.

“The GTR [Global Technical Regulations] takes a documentation approach on these aspects of safety because of the rapidly evolving electric vehicle technologies and the variety of available REESS and electric vehicle designs,” the notice states. “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.”

Manufacturers would also be required to provide, at NHTSA’s request, all known safety hazards, risk mitigation strategies for those safety hazards, and, if applicable, how they provide a warning to address a safety hazard.

NHTSA requests comments on the possibility of applying aspects of FMVSS No. 305a to low-speed EVs that may be at risk of causing shock and fire.

Comments on the overall proposal are also requested through June 14.

A separate NPRM, broken down into two FMVSS documents, addresses safety risks associated with hydrogen-powered vehicles because of the necessity to compress hydrogen to high pressures to serve as an efficient motor fuel, NHTSA states in the NPRM. As with other motor fuels, hydrogen is also highly flammable.

While NHTSA has regulations in place to ensure the safe containment of other motor vehicle fuels such as gasoline and compressed natural gas and their fuel integrity systems no such regulations exist for hydrogen gas.

NHTSA’s two proposed federal standards would regulate the integrity of the fuel system in hydrogen vehicles during normal vehicle operations and after crashes and the compressed hydrogen storage system (CHSS) itself.

Fuel system regulations would include performance requirements to mitigate hydrogen leakage and discharge as well as post-crash restrictions on hydrogen leakage, concentration in enclosed spaces, container displacement, and fire. CHSS standards would primarily cover performance requirements to prevent hydrogen leaks or bursts and to ensure hydrogen is safely expelled from the container when exposed to a fire.

Compliance would be required two years from publication of the final rule in the Federal Register, which is slated to be Sept. 1. Public comments close June 17.

Images

Featured image: An electric vehicle (EV) is shown burnt after the fire it was involved in was extinguished. (Credit: CIC)

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