Lithium-ion battery fire Fires are intense and scary. As someone who used to repair used smartphones, I have put out many iPhones that were burning due to punctured lithium-ion batteries. And the smartphone battery in your pocket right now is similar to the battery in an electric car. However, EV batteries store much more energy. So much energy that some firefighters are specially trained to put out the extremely intense EV fires that are released from burning EV batteries after road accidents.
If you read the news about EVs, you’ve probably seen a lot of scary stories about the rise in battery fires. Recently, the National Transportation Safety Board and the California Highway Patrol announced they were investigating a fire in a Tesla lorry that broke out after the vehicle struck a tree. The lithium-ion battery continued to burn for about four hours.
Does this mean we should be worried that our personal electric vehicles might be a fire hazard? Not necessarily. EVs are less likely to catch fire than traditional forms of transportation, so it makes more sense to be worried about a gasoline-powered car catching fire rather than an electric car.
“Battery manufacturing defects causing a fire are really, really rare,” says Matthew McDowell, co-director of Georgia Tech’s Advanced Battery Center, “but it’s more likely, especially in electric vehicles, because they also have battery management systems.” This software monitors the various cells that make up an EV’s battery and helps prevent the battery from exceeding its limits.
How do electric car fires start?
If an EV battery is damaged in a crash, it can catch fire due to a phenomenon called thermal runaway. EV batteries are not one solid brick. Rather, think of them as a collection of many smaller batteries, called cells, pressed together. In thermal runaway, a chemical reaction occurs in one of the cells that starts a fire first, and that heat quickly spreads to adjacent cells, causing the entire EV battery to burn.
Greg Less, director of the University of Michigan’s Battery Institute, separates EV battery fires into two clear categories: accidents and manufacturing defects. Less considers accidents to be anything from a crash that punctures the battery to a charging error. “Let’s rule out accidents,” Less says, “because I think we all understand that no matter what type of car it is, if you get into an accident, there’s a chance that you could have a fire.”
While all EV battery fires are difficult to extinguish, fires caused by manufacturing defects are likely to be of more concern to consumers because they seem random. (Remember when Samsung recalled all of their phones because of battery issues that posed a fire hazard?) How do these rare issues in the manufacturing of EV batteries cause fires that feel like random moments?
It all comes down to the battery design. “There was a problem somewhere in the design, and the cells shorted out and started to heat up,” says Les. “The heat caused the liquid electrolyte to evaporate, creating gases inside the cells. If the heat gets high enough, it ignites and explodes, spreading to the other cells.” Recent highly publicized electric car fires in South Korea were likely caused by such defects; one of them damaged more than 100 vehicles in a parking lot.
What to do if your EV catches fire
According to the United States Fire Administration, if your electric vehicle catches fire while you’re driving, immediately find a safe place to move the vehicle off the main road. Then, turn off the engine and have everyone exit the vehicle immediately. Don’t slow the situation down by grabbing personal belongings, just get out of the car. Stay at least 100 feet away from the burning vehicle when you call 911 to notify the fire department.
Also, do not try to put out the fire yourself. This is a chemical fire, so a few buckets of water will not be enough to put out the fire. It takes about 10 times more water to put out an EV battery fire than a gasoline-powered car fire. Firefighters may decide not to douse the battery with water and instead let it burn out naturally.
