Lithium batteries can ignite weeks after a crash - but EVs not necessarily more fire prone than gas vehicles
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There is a large interest in lithium-ion battery fires across the firefighting community. There is no strong evidence that EVs are more likely to catch fire than conventional fuel cars - but what can be a concern, not just for firefighters, is the possibility of an EV catching fire several weeks after a crash.
Another heavy concern is that lithium-Ion EV batteries are difficult to extinguish and may require a lot of water, depending on the situation and the equipment availiable in the accident scene .In some extreme cases EV fires have required 30,000 gallons / 110,000 liters of water to extinguish. The amount of water needed may be different from case to case, but many fire services often count on using at least as much water on an EV fire as on a regular house fire.
With growing environmental concerns, and scarcity of water during hot summer months, using several tanker trucks worth of water on a single EV fire can become expensive as sales of EVs increase in coming years.
As the CTIF Commission for Extrication and New Technology has argued for many years, standardized methods for extinguishing lithium fires and the knowledge how to safely extricate EVs after a crash, and how to best extinguish fires, is necessary for firefighters and the public to be safe as the "electric revolution" continues.
Tesla ignited in a junkyard
In June 2022, a team of firefighters from the Sacramento Metropolitan Fire District arrived to a fire at an auto wrecker. A crashed Tesla Model S had been sitting in the junkyard for three weeks when it spontaneously ignited, as reported in the fire department´s Instagram account.
"Working with the on-site wrecking yard personnel, the Tesla was moved on its side to gain access to the battery compartment underneath. Even with direct penetration, the vehicle would still re-ignite due to the residual heat", the fire department wrote in their post.
As CTIF.org has reported previously, the Sacramento Fire Department then did an interesting "ad hoc" solution to the problem by digging a hole in the ground in order to place the EV in a pool of water.
"Crews and on-site personnel then created a small pit, placed the car inside it, and filled the pit with water effectively submerging the battery compartment. The pit ultimately reduced the total amount of water needed, estimated at 4500 gallons, and limited the runoff of contaminated water. The vehicle was fully extinguished, and no injuries were reported", the fire department wrote.
Tractor used to dig a water pool to submerge the EV
According to an article in the Washington Post on June 22, 2022, the fire fighting team... "used a tractor to create a pit in the dirt, managed to get the car inside, then filled the hole with water. That allowed the firefighters to submerge the battery pack and ultimately extinguish the fire, which burned hotter than 3,000 degrees, Capt. Parker Wilbourn, a fire department spokesman, told The Washington Post.
So how common are EV fires really? In an article on Autoweek.com from October, 2022, researchers from insurance deal site Auto Insurance EZ compiled sales and accident data from the US Bureau of Transportation Statistics and the National Transportation Safety Board.
They found that hybrid vehicles to be the most prone to catch fire, followed by gasoline vehicles.
According to the compiled statistics, hybrid vehicles had the most fires per at 3474.5 per 100,000 sales.
There were 1529.9 fires per 100k for gas vehicles and just 25.1 fires per 100k sales for electric vehicles.
"EVs are still novel and still unknown to a large portion of the public. News and media outlets report on electric car fires more often because of its, which can make it seem like they are a common occurrence", says the article on Autoweek.
An October 2022 article on CRSAutomotive.com make a similar conclusion, however also cautions that more scientific data is needed to be sure.
The article also states a delay in ignition, due to the chemistry of batteries as opposed to gasoline, is what primarily differs in a crash between gasoline powered vehicles and EVs.
"... Gasoline fires start almost immediately when gasoline comes in contact with a spark or flame and spreads rapidly. Battery fires typically take some time to achieve the heat necessary to start the fire... In some instances, that delay is very good news. It can let the occupants of a car involved in a crash get out of the vehicle before the fire starts. But it can pose its own problems", states the article.
Training and standardized methods necessary
The issue, rather than the inherent flammability of the the lithium batteries, is, according to Autoweek, rather a matter of training, new methods and public awareness of how EV fires behave.
Lithium-ion batteries burn hotter and can last much longer than gas, which tends to burn out quickly. Lithium-ion battery fires can take tens of thousands of gallons of water to extinguish. The National Fire Protection Association notes that one EV fire in Texas required more than 30,000 gallons of water after a crash.
"Fire departments aren't always equipped with trucks and other gear to deal with that. Emergency responders and firefighters must follow different response guides than for gasoline fires, and need training to properly extinguish the blaze".
The US National Transportation Safety Board (NTSB) has also found that many automakers still have incomplete or inadequate emergency response guide notes on EVs.
This is an area where CTIF has been working intensively with the automotive industry and Euro NCAP to provide firefighters with standardized rescue sheets for all vehicle types. The CTIF Commission for Extrication and New Technology started already in 2016 to develop the ISO 17840 Standard for vehicle firefighting, including rescue sheets downloadable through a smart phone app, and propulsion identification stickers for all heavy vehicles.
This puts Europe somewhat ahead of the rest of the world, where car safety testing organisations like NCAP have not yet managed to implement this important standard.