Are Electric Vehicles More Likely To Catch on Fire?

Electric vehicles (EVs) have been around for more than a decade. While EV sales have greatly increased over the past eight years, they account for less than two percent of all vehicles on U.S. roads.

Because they remain a curiosity, highly publicized EV battery fires and battery recalls make EVs appear more dangerous than a gas-powered car. Here’s what you need to know.

Is an Electric Vehicle Fire More Common Than a Gas-Powered Car Fire?

No, according to Kelley Blue Book, a trusted and reliable industry source. Gas-powered internal combustion engine (ICE) vehicles use a 12-volt lead acid battery to start the car. The electrolyte, a mixture of sulfuric acid and distilled water, that creates electricity in a lead acid battery rarely ignites under normal driving conditions.

However, in an ICE vehicle:

• Sparks from a faulty electrical system or an accident can quickly ignite gasoline.
• Extremely combustible fluids (engine oil or transmission, power steering and brake fluid) are why an ICE vehicle could burst into flames.
• A backfiring or poorly running engine can overheat a catalytic converter to temperatures reaching 1,400 degrees. Though the catalytic converter won’t catch fire, at this temperature it can easily ignite anything nearby, including other parts of the car or leaking fluids from an inadequately maintained engine.

Many EVs also have a 12-volt lead acid battery to operate lights and the radio, but it’s the high-voltage lithium-ion battery that can catch fire. Lithium-ion batteries contain easily flammable organic solvents and gases, plus oxygen-rich electrolyte.

How Common Are Electric Vehicle Battery Fires?

Current available data show EV battery fires are rare in fully plug-in vehicles.

The National Fire Protection Association (NFAP) and the Bureau of Transportation Statistics report, on average, 170,000 vehicles a year catch fire in the U.S., without differentiating between ICE and EVs.

Vehicles that catch fire fit into these categories:

• Forty-five percent from mechanical malfunctions or neglect;
• Twenty-three percent from electrical wire or cable insulation failures;
• Five percent due to collisions or vehicles overturning;
• Twenty-seven percent from carelessness or unintentional action.

Safety note: This is a good reason to keep a fire extinguisher in your vehicle.

Using data from the National Transportation Safety Board (NTSB), Bureau of Transportation Statistics (BTS) and government recall information, AutoinsuranceEZ indicated fires by vehicle type:

• Hybrids reflected the most at 3,475 fires per 100,000 vehicles. This is most likely because hybrids utilize two powertrains.
• ICE vehicles caught fire substantially less often, at 1,530 incidents per 100,000 vehicles.
• EV fires were significantly lower than the others, with 25 fires per 100,000 vehicles. So of the approximately two million EVs on U.S. roads, less than two out of a 1,000 will catch fire.

Per AutoinsuranceEZ, ICE vehicles are more than 60 times more likely to catch fire than an EV, while hybrids are more than 130 times more likely to catch fire than an EV.

What Starts an EV Battery Fire?

According to an NTSB report, lithium-ion EV battery fires happened after a crash. High-voltage battery packs can be punctured on impact, or wiring and cables can short circuit. A spark from a short circuit can ignite the battery’s flammable organic solvents, setting individual cells ablaze, which overheat and ignite other cells.

Thermal runaway is another major cause. According to UL Research Institutes, thermal runaway is “a phenomenon in which the lithium-ion cell enters an uncontrollable, self-heating state.” If the heat can’t disappate normally, it can lead to a fire.

Lots of things can trigger thermal runaway, from poor battery design and ventilation to charging the battery before it cools down. This phenomenon affects all lithium-ion batteries, including those in your smartphone and electric toothbrush.

Is It Harder to Extinguish an EV Fire?

Yes. The safety risks to first responders dealing with an EV battery fire are significant.

Once the organic solvents and flammable gases ignite, they feed on the electrolyte, causing a self-sustaining, difficult-to-extinguish fire. An internet myth that water cannot extinguish an EV battery fire is false; it can.

According to Chief Palmer Buck of The Woodlands Township in Austin, TX., his department can extinguish a gasoline-fueled car fire with 500 gallons of water they carry on their trucks. However, it can take 3,000 gallons or more to extinguish an EV battery fire. Firefighters also need special training to extinguish EV fires, combining water with firefighting foams that quickly cool down the battery.

High voltage is another danger in EV fires. To reduce the risks to first responders, all major EV manufacturers have teamed with the NFAP to create Emergency Response Guides that include steps to safely disable the high voltage system.

How To Reduce the Chance of an EV Battery Fire

Daily monitoring of the battery’s condition and powering down if the high volt battery warning light comes on can help prevent a fire and extend battery life. Use the numerous built-in interactive visual tools that provide detailed graphic data of the charging system’s health, including:

• Energy usage details;
• High voltage power flow;
• Charging status;
• Efficiency history;
• Estimate driving range based on temperature, driving practices, electrical load and road conditions.

Third-party apps monitor your vehicle’s battery management system and deliver a monthly health report.

Other steps to take include:

• Have the underside of your car inspected after an accident or driving over road debris.
• Check if your vehicle is under a safety or battery recall. Subscribe at Recall.gov to receive recall notifications from the NHTSA and other government agencies.
• Have your EV batteries checked for leakage and corrosion as part of a regular maintenance schedule.
• Let the battery completely cool before charging.
• Park in the shade whenever possible.
• Use only approved, compatible Level 1 and 2 battery chargers.
• Never use a cracked or damaged charging cord plug.
• Charge your EV in a well-ventilated area.
• Keep the battery between 20 and 80 percent charged. Charging to 80 percent leaves room for energy from regenerative braking, reducing the likelihood of overheating.
• Disconnect when charged to 80 percent.
• Check the battery coolant levels frequently.
• Ensure battery management system software is up-to-date.
• Check weather conditions before charging. Don’t charge the battery in the rain.

Are EV Batteries Safe?

Yes. Although EV battery technology is in its infancy, several substantial advancements have already been made to EV lithium-ion batteries.

The addition of more sensitive sensors, better construction methods and more stable solid electrolytes are making EV batteries less prone to overheating and thermal runaway.

Soon, expect to see solid-state batteries and flammable materials replaced by lighter, safer materials made from carbon fiber and possibly even crab shells.