A Tesla combusted Wednesday in Hurricane Idalia floodwaters near Tampa, prompting officials to remind residents of the dangers of electric vehicles coming in contact with saltwater.

Dunedin Fire Rescue, located in Pinellas County west of Tampa, confirmed crews responded to a fire Wednesday afternoon, hours after Hurricane Idalia blew by in the Gulf of Mexico.

"If you own a hybrid or electric vehicle that has come into contact with saltwater due to recent flooding within the last 24 hours, it is crucial to relocate the vehicle from your garage without delay," the a post by nearby Palm Harbor Fire Rescue reads. "Saltwater exposure can trigger combustion in lithium-ion batteries. If possible, transfer your vehicle to higher ground."

Even in extreme circumstances, electric vehicle fires are relatively rare. An estimated 358,000 vehicles were damaged from Hurricane Ian’s widespread flooding in Florida and the Carolinas and only 21 electric vehicles are known to have burned — a number much lower than some officials initially warned of. But the fires can be dangerous, so officials are preparing in the aftermath of Idalia.

Florida braced for EV fires in Hurricane Idalia flooding

As reported by 10 Tampa Bay, Florida Gov. Ron DeSantis warned about EV fires as Hurricane Idalia drew closer.

“These electric vehicles when they get saltwater intrusion can catch on fire and those are very difficult fires to put out,” DeSantis said during a storm update.

Florida CFO Jimmy Patronis witnessed an EV fire after Hurricane Ian that reignited several times, as he said in a statement warning people to move their cars to higher ground.

Golf carts and scooters are subject to the same risk, Patronis said.

Tampa Fire Rescue posted about safety tips for EVs in the wake of Hurricane Idalia. But as of Friday morning, they had not responded to any EV fires due to floodwater.

"We wanted to be preemptive," said spokesperson Vivian Shedd. "We weren't with (Hurricane) Ian."

21 electric vehicle fires after 2022 Hurricane Ian

According to Patronis, who also serves as the Florida State Fire Marshal, there were 21 fires related to EVs in the aftermath of Hurricane Ian, which struck Southwest Florida in September 2022. The catastrophic storm caused $115.2 billion in damages, killed 156 people and knocked out power for 2.6 million residents.

One incident on Sanibel Island near Fort Meyers, Fla. gutted the house the car was parked in and the house next door.

Those fires weren't a total surprise either. The dangers of flooding for EVs had been known since Superstorm Sandy in 2012.

EVs less likely to catch fire than gas cars

Statistics compiled by AutoInsuranceEZ found that for every 100,000 EVs, there are about 25 fires each year. That compares to 1,530 car fires in the same number of gas-powered vehicles annually. Gas-powered cars typically catch fire due to fuel leaks or crashes.

Why do flooded EVs catch fire?

If an electric vehicle’s battery is damaged by a collision or water intrusion from a flood, a short circuit can occur, which causes the cell to discharge energy and heat up. This can lead to an event called “thermal runaway,” in which the heat propagates from one cell to the next, causing them to burn.

In a small number of cases when an EV is submerged in water, contaminants or salt in the water can cause short-circuiting, especially after the water drains from the battery.

Vehicles or batteries that have been damaged also have the potential for short-circuiting to occur due to movement of the vehicle or battery, for example when it's being loaded or unloaded from a tow truck.

Heat generated from a fire, thermal runaway of an adjacent cell, or shorting of the battery can melt the porous membrane between the battery’s cathode and anode, causing this cell to go into thermal runaway. The heat causes the cell to vent flammable gas, which can ignite and catch fire. 

"That heat can get transferred to the next cell and it can become a chain reaction," said said Thomas Barth, chief of the special investigations branch of highway safety at the National Transportation Safety Board.

"If you have a damaged lithium-ion battery and it has energy which remains in the battery pack, we call that stranded energy," he said. "If you initiate a thermal runaway or venting of the flammable gas, the battery can ignite." 

Experts warn that it is not necessarily likely for a EV to catch fire just because it has flooded. Only a small percentage of registered EVs caught fire, according to USA TODAY analyses.