How often do electric cars catch fire?

Krzysztof Smejlis/

Given the intense stories Regarding electric vehicle fires and past disasters involving overheated lithium ion cell phone batteries, it is reasonable to worry about an electric vehicle (EV) battery catching fire. But how often does that actually happen, and why?

Are EVs more likely to catch fire than gas cars?

Compared to how long gas cars have been around, there isn’t much data on fires in electric vehicles at the time of writing. But there is enough to make some observations. Car insuranceEZ compared data from multiple sources to find an answer to the question of how often electric cars catch on fire.

Their sources were:

National Transportation Safety Board (NTSB) Bureau of Transportation Statistics (BTS)

In fact, per 100,000 vehicles sold, it was hybrids that had the most fires, and battery-powered electric vehicles the least. As for the vehicle type with the highest total number of fires, they were by far petrol cars. Recall data showed that several components can cause a fire in a gasoline car, but with EVs and hybrids, it was almost always the battery.

Overall, EVs had about a 0.3% chance of catching fire, while gasoline-powered cars had a 1.05% chance of igniting. That should be good news for EV owners, but as the AutoinsuranceEZ report points out, car fires are dangerous, regardless of the cause.

EV fires are rarer, but harder to put out

While the data shows that EV fires are rarer than gasoline car fires, EV car fires burn hotter and for a longer period of time. In gas cars there is usually a single reaction, such as a spark in a pool of gasoline, that leads to a fire and that reaction eventually burns off. When an EV’s lithium-ion battery ignites, the battery burns the energy stored in it, making it the main source of energy for the fire and taking much longer to use itself.

Lithium-ion traction batteries are designed to contain a huge amount of energy in a very small space. Each cell in it is filled with a flammable electrolyte, as well as electrodes that can short circuit if damaged or not properly maintained, causing the cell to overheat.

When a cell overheats, it can enter a process called thermal runaway – basically a positive feedback loop where it makes itself hotter very quickly – igniting the adjacent cells in the battery pack until the whole thing goes up. Lithium-ion batteries can also re-ignite after being extinguished if they cause further damage to or short-circuit the battery by moving.

Because first responders are usually trained in putting out gasoline car fires, they may have trouble putting out an EV fire because it behaves differently. Instead of cooling the part of the car that a firefighter would normally do, they should: direct water to the bottom of the vehicle containing the battery pack. Stored energy left in the battery, called stranded energy, can cause the battery to re-ignite hours or even days after the initial fire has been extinguished if that energy is not properly handled.

What can cause an electric car to catch fire?

Multiple factors can cause a fire in an electric car, mostly related to the battery. For example, if the battery is damaged in a crash, it can short-circuit one or more of the lithium-ion cells and set off a thermal chain reaction.

If poorly maintained, components in the battery pack can deteriorate to such an extent that a malfunction causes a fire. Manufacturing defects can also be the cause of car fires, both in EVs and petrol vehicles.

Age can also be a factor. There isn’t enough data yet to show whether electric car batteries from roughly 20 years old pose a greater fire risk, but it’s something to consider as the components can deteriorate over time with heavy use and poor performance. maintenance.

Should you be concerned about electric car fires?

The bottom line at the time of writing is that EV fires are much rarer than gasoline car fires. They are also much hotter, burn longer and can therefore be very dangerous.

This does not necessarily mean that all electric vehicles are more dangerous than gas vehicles, just that standardized safety guidelines need to be developed to deal with these fires if and when they do occur. If you have one, make sure you maintain the components well to keep the risk low.

RELATED: Why Does an Electric Car Battery Deteriorate?

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