Electric vehicle fire warning

FloridaElectric cars can catch fire if submerged in salt water, so owners who live in the path of a large storm like Hurricane Helen should take precautions and prepare for the possibility of not being able to charge their cars during a power outage.

What can electric car owners do?

Florida Gov. Ron DeSantis this week urged electric vehicle owners to move them to higher ground before Hurricane Helen hits. Although the problem is rare, in recent years several cases of electric cars catching fire after hurricanes have been reported.

Keeping electric vehicles away from standing water is the best way to avoid the possibility of a fire.

Tesla offers similar advice about preventing its cars from being submerged if possible, but if that happens, the automaker suggests towing the car at least 50 feet away from structures or anything flammable so a mechanic can inspect it.

The best way to get through a power outage is to follow the same advice your dad gave you about keeping your gas tank full to make sure you don’t get stranded. Keeping your electric vehicle charged offers the most flexibility.

Of course, EV owners won’t be able to charge their cars during a power outage, so they may need to monitor their mileage. But electric cars are no worse off than conventional cars because gas stations also cannot refuel during power outages.

How common are electric vehicle fires after a flood?

The National Highway Traffic Safety Administration has investigated this problem since it was first noticed after Hurricane Sandy hit the Northeast in 2012. But no one seems to have detailed statistics on how often it happens.

Two years ago, Hurricane Ian damaged the batteries of about 5,000 electric cars and 36 of them caught fire.

Last year, several electric cars caught fire in Florida after Hurricane Idalia, although that storm was weaker than Ian. NHTSA investigators speculated that the fact that more people were aware of the problem and had moved their vehicles to higher ground before that storm may also have helped.

But it often happens that officials in Florida were concerned about this possibility before Hurricane Helen hit because they expected a potentially devastating storm surge up to 20 feet deep in the northwestern part of Florida.

These fires appear to be specifically linked to salt water, as salt can conduct electricity. Similar problems were not reported after freshwater flooding in California due to heavy rains earlier this year.

What causes electric cars to catch fire?

Electric vehicles with lithium-ion batteries can catch fire if the batteries short-circuit and begin to overheat. If heat starts to spread between the different cells on the back of the battery, it could cause a chain reaction called thermal runaway, said Tom Barth of the National Transportation Safety Board.

“If salt water can penetrate the space between the positive and negative terminals of the battery, it could cause a short circuit,” said Barth, who is chief of the Special Investigations Division of the National Highway Traffic Safety Board’s Office of Highway Safety.

Car manufacturers design their batteries to try to avoid this problem. There are often gaps or insulating barriers between the different cells in a battery pack, and manufacturers take measures to prevent moisture, but they must include methods that allow the batteries to release heat.

“The problem starts when the batteries are immersed in standing water, as the moisture begins to overcome the battery seals,” Barth said.

Sometimes, electric cars can catch fire long after floodwaters have receded, because even after the water evaporates, electrically conductive salt may remain. This is why it is important to check it if it is submerged in water.

“It’s not that all vehicles that are exposed to flooding will catch fire,” Barth said.

The National Highway Traffic Safety Administration (NHTSA) said it is working to improve battery safety as officials learn more about the problems. The agency proposed updating some safety requirements for electric vehicle batteries to reduce risks.