Electric vehicles could ignite during Hurricane Milton: Here’s what to know to avoid a fire

ST. PETERSBURG, Fla. - Electric vehicles can catch fire if they are inundated by saltwater, so owners who live in the path of a major storm like Hurricane Milton should take precautions and prepare for the possibility that they’ll be unable to charge their cars during a power outage.

After Hurricane Helene skirted the Bay Area before making landfall in Florida’s Big Bend Area, it created a storm surge that flooded some electric vehicles, causing them to catch fire and, in some cases, ignite homes.

What can EV owners do?

Ahead of Hurricane Helene, Florida Gov. Ron DeSantis urged EV owners to get their vehicles to higher ground before the storm arrived. Although the problem is rare, there have been a number of instances in recent years of electric vehicles igniting after hurricanes.

WATCH: Electric vehicle flooded in saltwater catches fire in Siesta Key

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

Tesla offers similar advice about avoiding letting its vehicles become submerged if at all possible, but if that does happen, the carmaker suggests towing the vehicle at least 50 feet away from structures or anything combustible until it can be inspected by a mechanic.

The city of St. Petersburg is encouraging EV owners to take the following steps to prepare ahead of Hurricane Milton:

Maintaining your battery at 100% state of charge. If you plan on evacuating in an EV, keep your vehicle’s range in mind and avoid relying on charging stations along the evacuation routes as they may experience long lines or power outages.
Never drive through floodwater. Water infiltration can damage the battery, heightening the risk of a battery fire, which can erupt instantaneously or manifest days, weeks, or even months after exposure to salt water.
Store your EV properly. If you are leaving your EV behind to evacuate, park outside of flood-prone areas and at least 50 feet away from any structure or other vehicles, do not leave your EV plugged into a charger, and maintain the battery at less than 30% state of charge.

After the storm:

Never try to drive or charge a vehicle that has been submerged in floodwaters.
Properly dispose of any lithium-ion batteries containing lithium-ion batteries exposed to floodwaters. Do not toss these batteries in a regular trash can.

How common are EV fires after flooding?

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

Two years ago, Hurricane Ian compromised the batteries of as may as 5,000 electric vehicles, and 36 of them caught fire.

READ: At least two Pinellas EVs catch fire after Idalia storm surge compromises batteries

Several more electric vehicles caught fire in Florida last year after Hurricane Idalia, although that storm was weaker than Ian. Researchers at NHTSA speculated that it may have also helped that more people were aware of the problem and moved their vehicles to higher ground before that storm.

But it happens often enough that Florida officials were worried about the possibility before Hurricane Helene arrived because they were expecting a potentially devastating storm surge up to 20 feet deep in the northwestern part of Florida.

These fires do seem to be linked specifically to saltwater because salt can conduct electricity. Similar problems haven’t been reported after freshwater flooding in California that was driven by heavy rains early this year.

What causes EVs to catch fire?

Electric vehicles with lithium-ion batteries can catch fire if the batteries short circuit and start to heat up. Tom Barth with the National Transportation Safety Board said that if the heat starts to spread between different cells in the battery pack, it can cause a chain reaction called thermal runaway.

"If the saltwater is able to bridge the gap between the positive and negative terminals of the battery, then it can cause a short circuit," said Barth, who is chief of the special investigations branch of the NTSB’s office of highway safety.

Carmakers do design their batteries to try to prevent this problem. There are often separations or insulation barriers between different cells in the battery pack, and manufacturers take steps to keep moisture out. But they do have to include ways for the batteries to vent heat.

READ: E-bike found submerged in Hurricane Helene flooding prompts hazmat response at Treasure Island resort

"Where it begins to be a problem is if you have the batteries submerged in standing water. That’s where it starts to overcome the moisture seals in the battery," Barth said.

Sometimes electric vehicles can catch fire long after the floodwaters have receded because even after the water evaporates, salt that can conduct electricity may be left behind. So it’s important to have them checked out if they are submerged.

"It’s not like every vehicle that gets flooded is therefore going to ignite and catch fire," Barth said.

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

The Associated Press contributed to this report.

STAY CONNECTED WITH FOX 13 TAMPA: