While electric vehicles are a growing trend nationwide in the pupil transportation industry, the National Transportation Safety Board cautions that little research has been conducted on how lithium-ion batteries react in a crash.
That is the focus of the NTSB safety report, “Safety Risks to Emergency Responders from Lithium-Ion Battery Fires in Electric Vehicles” that was released this week. It was accompanied by a video on the safety risks to emergency responders. NTSB concluded that vehicle manufacturer emergency response guides for emergency personnel are inadequate and gaps are present in safety standards and research-related to high-voltage, lithium-ion batteries involved in high-speed, high-severity crashes. NTSB issued several new recommendations to the National Highway Traffic Safety Administration, electric vehicle manufactures and fire and tow associations.
The report, which studied three electric vehicle crashes, illustrated the risk to emergency responders by the vehicles’ high-voltage, lithium-ion batteries. The NTSB also examined national and international standards to maximize the safety of electric vehicles, with a focus on emergency guidance documents supplied by vehicle manufactures to mitigate the safety risks to those responding to the fire.
In conducting the report, the NTSB investigated several high-voltage battery fires in electric vehicles occurring in the U.S. between August 2017 to August 2018. In three of the four battery fires investigated, the battery was damaged in a high-speed, high-severity crash that ignited the batteries. Yet after firefighters extinguished the initial fire, smoke, popping noises from the battery, or reignited flames occurred. In the fourth crash, a fire occurred during normal vehicle operations and did not reignite.
Despite all four vehicles involved being a Tesla car or SUV, NTSB said its intent was to study vehicle fires caused by high-voltage, lithium-ion batteries, not the vehicle design. The NTSB also studied a controlled electric fire at a test facility as well as several international vehicle fires that all posed similar problems to emergency responders when the battery case or battery cells were damaged or failed internally.
In its analysis, the NTSB reviewed guidance documents prepared for emergency responders by 36 manufacturers of electric vehicles powered by high-voltage, lithium-ion batteries. It concluded that guidance was strong in certain areas but lacking in others, particularly regarding specific instruction for fighting these fires.
The NTSB guidance evaluated documents specifically related to high voltage disconnect, fire suppression, thermal runaway and battery reignition, “stranded energy,” and format issues.
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The NTSB recommended to NHTSA it factor in the availability of a manufacturer’s emergency response guide and its adherence to International Organization for Standardization standard 17840 and SAE International recommended practice J2990 when determining a vehicle’s U.S. New Car Assessment Program Score.
NTSB also seeks an NHTSA-created coalition of stakeholders to continue researching ways to mitigate or de-energize the “stranded energy” in high-voltage, lithium-ion batteries, and to reduce hazards associated with thermal runaway in high-speed crashes. NTSB calls on NHTSA to publish its research results.
To the manufacturers of electric vehicles equipped with high-voltage, lithium-ion batteries, including Tesla, NTSB recommends model emergency response guides be developed and based on International Organization for Standardization standard 17840, as included in SAE International J2990 recommended practice.
NTSB also says manufacturers should incorporate vehicle-specific information on fighting high-voltage lithium-ion, battery fires, mitigating thermal runaway and the risk of high-voltage lithium-ion battery reignition, mitigating the risks associated with “stranded energy” in high-voltage, lithium-ion batteries, both during the initial emergency response and before moving a damaged electric vehicle from the scene, and safely storing an electric vehicle that has a damaged high-voltage, lithium-ion battery.
NTSB also asked the National Fire Protection Association, the International Association of Fire Chiefs, the International Association of Fire Fighters, the National Alternative Fuels Training Consortium, the National Volunteer Fire Council, and the Towing and the Recovery Association of America to inform all members of the circumstances of fire risks as described in this report and make the guidance available to emergency personnel who respond to such incidents.