Clearing the air: Emerging data and battery trends suggest EVs could bring lower fire risk

Emerging data tells us that electric vehicles (EVs) don’t have any higher fire risk than conventional combustion engine vehicles. According to Andrew Klock, senior manager of education and development at the National Fire Protection Association, EVs are “not more dangerous. They’re just different.”

Understanding battery fires

EV battery fires involve thermal runaway, a chemical process that occurs when one of the cells in a battery pack short circuits and heats up unsafely. The heat from the malfunctioning cell can cause the adjacent cells to fail, and this can lead to a chain reaction in the battery pack. Compromised battery cells release oxygen that fuels a fire during thermal runaway. This can be slowed and eliminated by lowering the temperature enough to make the chemical process stop. Directly targeting the battery pack with water to gradually lower the temperature stops EV fires. Currently, it can take around 2,500 gallons to extinguish an EV fire; a combustion engine fire can take about 500–1,100 gallons.

Thermal runaway is more common in certain battery chemistries than in others, and lithium-ion batteries made with nickel manganese and cobalt oxide (NMC) cathodes have relatively greater fire risk than other chemistries. But there’s good news here: The battery industry is shifting toward nickel- and cobalt-free lithium iron phosphate (LFP) cathodes and LFP batteries have high thermal stability that makes them less prone to thermal runaway. Assuming the shift continues, EV fire risk will be reduced over time. Next-generation, solid-state batteries currently in development promise to reduce EV fire risks even further by replacing flammable, liquid electrolytes in lithium-ion batteries with non-flammable, solid electrolytes.

Battery fires by the numbers

According to data collected by EV FireSafe, an Australian company that monitors EV fires, there were slightly more than 500 battery-related fires in light-duty EVs globally between 2010 and the end of June 2024. With an estimated 40 million EVs operating globally as of early 2024, that’s around a 1 in 100,000 rate of fire. Tesla estimated that one of its vehicles caught fire every 130 million mi (209 million km) traveled, which is about one fire every 23,400 round trips from New York to Los Angeles. In comparison, the National Fire Protection Association estimated that a fire occurs once every 18 million mi (29 million km) for all fuel types, which is more than 7 times more frequent.

In the United States, there were on average 117,370 passenger vehicle fires each year between 2013 and 2017. That’s about one every 5 minutes. Although the U.S. data doesn’t identify which fires are in gasoline vehicles versus EVs, data in Sweden does. Based on that data, analysts at MotorTrend estimated that gasoline and diesel vehicles were 29 times more likely to catch fire than EVs and conventional non-plug-in hybrids.

In combustion engine vehicles, fire risk tends to increase with vehicle age, and the combustion engine fleet of vehicles is much older than the EV fleet. It will be important to monitor for trends as EVs increase in number and age.

Researching best practices

Research initiatives in multiple countries are investigating best practices for EV battery fires. For instance, the U.S. National Highway Traffic Safety Administration’s Battery Safety Initiative coordinates research and other activities to address safety risks related to EV batteries. This program collects data on incidents like crashes that can impact battery safety; conducts research into battery health monitoring, cybersecurity, and reasons for battery failures; and oversees recalls and investigations related to EV battery issues. It also proposes regulations, and a new proposal would require automakers to create and submit emergency response guides for each EV model.

Several countries that are implementing policies and regulations on EV fire safety could be models for how to proactively address EV fire concerns. Guidelines like installing more powerful sprinkler systems and smoke detectors inside parking structures and physical and chemical manufacturing requirements that improve battery cell safety are two examples. Also among the potential EV battery fire mitigation strategies are restrictions on where chargers can be installed in parking garages and requirements that chargers are physically protected from potential collisions with things like curbs or posts.

The bottom line

So while more research is aways helpful, the data we have so far is clear: EVs don’t have any higher fire risk than conventional gasoline cars. In fact, fires in aging gasoline powered cars happen much more frequently than EV fires. And as battery technology continues to improve and get safer, the EV fire risk will decrease even further.