Electric cars: this “thermal runaway” that alerts firefighters


Ua car that caught fire more than three weeks after arriving at the scrap yard, 17,000 gallons of water, the emergency construction of a mini-basin to immerse the electric batteries: The fire from a Tesla in early June surprised Sacramento District firefighters. The fire was extinguished but did not stop resuming. Even after turning the car on its side and directing the water directly at the batteries.

“We did not expect to face so many challenges” to control the flames, said Parker Wilbourn, captain of firefighters in the California metropolitan area.

With more and more hybrids and electrical appliances in circulation, “we are entering a new era of fires, we need to adapt and find solutions,” he believes.

Because “every second counts” during an incident, General Motors (GM) announced Thursday that it is expanding its first-aid training program to interventions on electric vehicles in the United States and Canada. The group is currently marketing four models in this category and aims to offer 30 by 2025.

The goal is to provide technical information about batteries, to share best practices and to “kill preconceived ideas”, explains a press release: think, for example, of stopping the engine as electric vehicles do not make noise, or combat the idea that you should not pour water on the batteries.

Electric and hybrid cars are still very much in the minority on U.S. roads, but they accounted for nearly 10% of the cars purchased in the U.S. last year, according to Cox Automotive.

The US Highway Safety Agency (NHTSA) says it does not have enough data on car fires with electric batteries to draw conclusions. But the latter are not a priori more frequent or dangerous than petrol cars, assures the National Association of Protection against Fires (NFPA).

On the other hand, they require specific procedures, adds the organization, which has been offering specific training since 2010.

Up to 30,000 liters for a Tesla

It usually takes much more water, between 11,350 liters and 30,300 liters approximately according to a guide prepared by Tesla for first aid attention. Which is not necessarily easy in rural areas where there are no fire hydrants.

It is also common for batteries to burn again for several hours or even days after the first event, due to a phenomenon known as “thermal runaway”, which can occur in damaged lithium-ion batteries. Tesla recommends monitoring battery temperatures for at least 24 hours after a fire.

“Firefighters are used to the risks” associated with electricity, notes Michael Gorin of the NFPA. “But not in a car.” Manufacturers are required to publish a first aid manual for each model they produce.

In a report published in late 2020, the US Transport Accident Investigation Board (NTSB) recommended that manufacturers of vehicles equipped with lithium-ion batteries follow the same format with specific information on how to extinguish and monitor a fire.

In early June, she pointed out that only eight producers out of the 22 affected had fully integrated her recommendations.

Hanging LG batteries

Firefighters arrive at accident sites “and do not know what to do,” notes Michael Brooks, legal director of the Center for Automotive Safety. “How do you evacuate a passenger from a burning electric vehicle? How do you know how the fire can spread?”

Like traditional cars, those equipped with batteries can also catch fire when stationary.

Last summer, GM advised owners of certain electric Chevrolet Bolts not to park them indoors or charge them unattended overnight before initiating a mass recall of the model.

Faults on batteries manufactured by the South Korean group LG can trigger fire outbreaks under certain circumstances. GM eventually had to suspend production of Bolt for several months. NHTSA initiated a specific procedure in April on LG batteries, involved in several recalls of the brands Volkswagen, Chrysler (Stellantis), Hyundai, GM and Mercedes.

All forms of transportation powered by electric batteries are affected: To prevent fires, the Agency for the Supervision of Social Housing in New York has proposed to ban in apartments and common areas all electric bicycles or batteries of electric bicycles, at least the same title as mopeds. So far, no official warning has been launched in France, although the technologies used and thus the risk factors are identical.

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