A spate of fires and product recalls in the past six months involving high-voltage, lithium-ion batteries in electric vehicles has led the US National Transportation Safety Board (NTSB) to issue safety recommendations for OEMs.
Safety Report 20/01 formed part of an investigation into the safety risks emergency responders face when dealing with high voltage, lithium-ion batteries in EVs.
The report identified the inadequacy of emergency response guides provided by vehicle OEM’s, and the gaps in safety standards and research related to high-voltage lithium-ion batteries involved in high-speed, high-severity crashes.
The NTSB’s four safety recommendations include: manufactures adhering to international safety standards, researching ways to mitigate thermal runaway, safely storing damaged EVs and providing suitable guidance for first responders. See below for full recommendations.
The report looked at how three of the four fires investigated were caused by lithium-ion batteries damaged in high-speed, high-severity crashes, and one occurred during normal vehicle operations.
NTSB found that all of the crash-damaged batteries reignited after firefighters extinguished the vehicle fires. The battery in the fourth investigation did not reignite.
Fires in EVs can pose the risk of electric shock to responders and thermal runaway arising from the ‘stranded’ energy that remains in a damaged battery.
Safety issues with the high-voltage, lithium-ion batteries in EVs first gained widespread attention when a Chevrolet Volt caught fire three weeks after a crash test in May 2011. NTSB first investigated an EV fire in 2017
In November, General Motors recalled 68,667 Chevrolet Bolt EVs with investigations opened into the reported fires made between 2017- 2019
In October, BEST reported how BMW and Hyundai were recalling vehicles to address issues with battery fires in plug-in models, Ford had delayed introducing its Escape plug-in after fire safety concerns, and an investigation was launched into the Chevy Bolt EV after three instances of fires.
Recommendations in full
- Factoring 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 U.S. New Car Assessment Program score.
- Continued research on ways to mitigate or deenergize stranded energy in high-voltage lithium-ion batteries.
- Continued research on ways to reduce the hazards associated with thermal runaway resulting from high-speed, high-severity crashes.
- Manufacturer emergency response guides modeled on ISO standard 17840 and SAE International recommended practice J2990.
- Incorporation of vehicle-specific information in emergency response guides for: Fighting high-voltage lithium-ion battery fires.
Mitigating thermal runaway and the risk of high-voltage lithium-ion battery reignition.
Mitigating risks associated with stranded energy in high-voltage lithium-ion batteries during emergency response and before a damaged electric vehicle is removed from the scene.
Safely storing an electric vehicle with a damaged high-voltage lithium-ion battery.
- Providing information and available guidance to first responders and other crash scene workers about fire risks associated with high-voltage lithium-ion battery fires in electric vehicles.
