Electric vehicle manufacturers should provide more specific information to first responders and tow truck drivers on how to cope with lithium-ion battery fires, which continuously reignite even after being doused with water, the National Transportation Safety Board said in a report released Wednesday.
The NTSB examined four fires in the US involving lithium-ion batteries from August 2017 to August 2018. Three of those started after crashes and a fourth ignited while the vehicle was operating. After all three crashes, the damaged batteries reignited after firefighters extinguished fires and continued to reignite at least 15 times.
The agency said first responders have adequate instruction from manufacturers on how to disconnect high-voltage batteries after crashes, but need more guidance on how to suppress thermal runaways — a heat-producing chain reaction often caused by “stranded energy” left in the undamaged portion of a battery. Manufacturers should also provide guidance to firefighters on how to suppress fires for specific vehicles, the report says.
Andrew Klock, emerging issues manager for the National Fire Protection Association, said he hopes the NTSB report will help educate first responders on the safety risks posed by lithium-ion battery fires. He said his organization has trained 250,000 firefighters on suppressing electric-vehicle fires, but there are 1.2 million in the United States and the majority of them are volunteers.
“I hope there is definite change,” Klock said. “I hope they come up with more emergency response guides and better safety features on the vehicles.”
Battery-powered cars are rapidly replacing electric vehicles as the dominant mode of surface transportation. According to an article in the latest issue of NFPA’s Journal, the number of electrical vehicles on the road is expected to grow from 3.1 million in 2017 to 130 million in 2030.
The NTSB says it started working with the Fire Protection Association to train first responders and tow operators on how to deal with lithium-ion batteries in late 2011, after a Chevrolet Volt caught fire three weeks after it had been wrecked in a crash test.
A short video that the NTSB released in conjunction with the report shows that firefighters are not always sure how to control electric-vehicle fires. In August 2017, the driver of a Tesla Model X was speeding at 82 mph in a residential area when he lost control and crashed into the garage of a house. The vehicle’s batteries started a fire that firefighters extinguished by pumping water on it.
About 45 minutes later, however, the Tesla began emitting heavy white smoke. Firefighters pumped water at a rate of 200 gallons per minute, but that did not extinguish the blaze. Firefighters were able to put out the fire only after increasing the flow to 600 gallons per minute and propping the vehicle up on cribbing blocks so they could spray water on the bottom of the vehicle where the batteries are located. It still took 45 minutes to extinguish the blaze.
The vehicle fire reignited when the Tesla was pulled onto a flatbed tow truck. Firefighters spent a total of six hours spraying water on the vehicle.
“Even though they applied a large amount of water, the underside of the vehicle kept reigniting and would not go out,” the report says. “According to the battalion chief, the fire crews reviewed emergency response guides and searched online for guidance on the appropriate action to take.”
Similar repeated reignitions were reported after a Tesla crash in Mountain View, Calif. in March 2018 and a Tesla crash in Fort Lauderdale, Fla. in May 2018. (Tesla produces 80% of the electric vehicles in the US.)
Klock said specific vehicle instructions would help firefighters know exactly where to aim their fire hoses. He said he would eventually like to see manufactures provide a specific safety feature to help extinguish fires, such as a nozzle that would aim water directly to the batteries.
The NTSB reviewed emergency response guides produced by 36 manufacturers of electric vehicles and found that none provided vehicle-specific instructions for suppressing high-voltage battery fires or information on coping with the stranded energy left in damaged batteries. The report says the batteries can produce up to 400 volts of energy, more than enough to fatally shock a first responder.
“If a crash damages the electrical isolation system, a person who touches the vehicle (or an exposed connector) can become part of the high-voltage circuit and suffer serious injury or death,” the report says.
The NTSB report recommends that:
- Manufacturers add vehicle-specific information to their emergency response guides.
- Emergency guidelines adhere to International Organization for Standardization standards.
- Research continue on ways to deenergize stranded energy in batteries and hazards associated with thermal runaway after high-speed crashes.
- Guidance be given to first responders on risks associated with high voltage lithium-ion batteries.
“The guidance documents generally limit their advice to calling the manufacturer for instructions or leaving at least 50 feet of clearance around the vehicle,” the report says. “The NTSB considers that advice impractical at best.”
About the photo: Firefighters respond to a Tesla Model X crash in Lake Forest, Calif. in August 2017. Photo provided to National Transportation Safety Board by the Orange County Sheriff’s Office.
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