Flash flooding in California caused by "potentially historic" rainfall from Tropical Storm Hilary could adversely affect the batteries of electric vehicles (EVs), after several caught fire after being exposed to flood waters in Florida in the wake of Hurricane Ian in 2022.
At least 12 EVs went up in smoke in the Sunshine State after their batteries were impacted by floodwaters, according to federal estimates. Fire officials laid the blame on seawater from a storm surge reacting with the batteries' components.
So far the flooding in California has predominantly been from heavy rains—but one expert warned that any flooding could be problematic for vehicles, including causing EVs to short-circuit.
California has far more EVs than any other state—in excess of 900,000 compared with just 168,000 in Florida, the state with the second highest number—and more than a third are estimated to be produced by Tesla, the market leader. Those pictured on fire in Florida following Hurricane Ian's devastation all appeared to be Tesla models.
Newsweek approached Tesla via email for comment on Monday. A spokesperson for the Electric Vehicle Association of America, which is based in California, said they had not received any reports of EV fires due to flooding in the state as of Monday.
The National Weather Service (NWS) issued a flash flood warning for parts of Southern California, including Los Angeles and Malibu, after Tropical Storm Hilary—which had been a category 4 hurricane at sea—made landfall on Sunday.
It forecast that in southwestern U.S. states, the "ongoing and potentially historic amount of rainfall" is expected to cause life-threatening or locally catastrophic flooding, including landslides and mudslides. Ahead of the storm's arrival, California Governor Gavin Newsom declared an emergency on Saturday.
"Floodwaters are problematic for any vehicles, not just battery electric vehicles," Greg Brannon, director of automotive engineering research at the American Automobile Association, told Newsweek.
"If there's flooding and you're not sure how deep the water is, don't drive through it," he advised. "And if your vehicle has been subjected to a flood condition, it needs to be inspected very, very carefully by someone [who] is authorized to do that.
"In many cases, you're going to find that those vehicles are no longer operable. Modern systems cannot get wet and dry out and just go about their business; the electronics can easily get corrosion and then there's any number of issues."
Brannon urged consumers who were considering buying a second-hand vehicle to ensure that it had not been subjected to flooding.
While Hilary is one of a handful of tropical storms to make landfall in California since records began, many more move in from the Atlantic to the Gulf of Mexico. Hurricane Ian was among the most intense hurricanes to hit the U.S., causing 150 deaths in Florida alone and bringing a storm surge as high as 15 feet with it.
At the time, Florida State Fire Marshal Jimmy Patronis told ABC News that his team had encountered nine instances of flooded EVs spontaneously combusting—in some cases, reigniting hours after being doused.
According to the U.S. Fire Administration, residual salt from seawater can form conductive bridges within batteries, which can in turn lead to short circuits and overheating. It noted that, in one case on Sanibel Island, off the coast of Cape Coral in Florida, two houses burned to the ground after an EV caught fire.
"The fact that it's saltwater or freshwater makes some difference, but not all the difference—the truth is any water is problematic and can cause shorting and damage to EV batteries," Brannon said.
He said internal combustion cars were "very unlikely" to catch fire after being exposed to water, outside of instances of flooding, and early data suggests that, overall, EVs are actually much less likely to combust than a conventional vehicle.
According to the latest research by AutoinsuranceEZ, generally there are over 1,500 fires for every 100,000 gas cars sold in the U.S., compared with 25 per 100,000 for EVs. The most common to catch fire were hybrid vehicles, it found.
However, when an EV does combust, it is harder and more time-consuming to put the fire out, as the components of an EV battery allow a blaze to produce its own heat and oxygen.
"In an electric vehicle, what can happen is that a short circuit can turn into a battery fire, and once an EV catches on fire and the main battery pack starts to burn, you can get into a situation which involves thermal runaway—which is basically a fancy way of saying that the battery is not only on fire but is also making oxygen that contributes to the fire," Brannon explained.
"That's why EV fires are so dangerous and difficult to put out," he added. "It's not as if you're burning a log in the fireplace; that log is now making its own oxygen and creating its own fire."
Fire officials also told ABC that extinguishing the flames from EVs required more water and time than those from a conventional car.
Uncommon Knowledge
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Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
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Aleks Phillips is a Newsweek U.S. News Reporter based in London. His focus is on U.S. politics and the environment. ... Read more
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