Are EVs Really Fire-Prone Death Traps?

Chances are, by now, you've seen footage of an EV on fire. It's a pretty scary sight. Evil, black smoke rolling out from under the car, possibly lit up by shooting sparks and ceaseless flames that seemingly no amount of water can extinguish. These fires are so often highlighted on the news and social media that it's easy to think they're happening all the time.

A high-profile Chevy Bolt recall related to possible fire risk certainly hasn't helped that public perception, providing ever more ammunition to anti-EV pundits who'd have you believe that parking an electric car in your garage is as good as playing with matches in a wood shed.

But if that were the truth, wouldn't we be seeing a heck of a lot more fires? Americans bought more than a half-million EVs in the first half of this year alone. What's the real truth about the fire risk of EVs? That's what we're here to find out in our latest installment of EV Myths, Discharged.

What causes EV fires?
Everyone knows what it takes to set gasoline on fire: A tiny little spark will do. Gasoline's combustible nature makes it ideally suited for internal combustion, but it's very happy for some external combustion, given half a chance.

Battery fires, however, are a little more nuanced. Your typical chemical cell in an EV is full of exotic components that you may be less familiar with, but the same combination of materials that creates a remarkably energy-dense source of power for your car can also create the perfect storm for a really ugly fire.

To get all the details, I highly recommend you check out "The Science of Fire and Explosion Hazards from Lithium-Ion Batteries” by Adam Barowy, research engineer at UL's Fire Safety Research Institute. It goes into way more detail than I possibly could here.

But the gist of it is that lithium-ion battery fires typically happen due to something called thermal runaway. This is when a battery cell begins to gain temperature faster than it can shed it. This can happen for a variety of reasons, including a flaw in the battery construction, or a failure during charging.

It can also be caused by physical damage to the cell, which might happen in a catastrophic crash or if you happen to drive over debris that somehow manages to pierce the cell. This can cause a short in the battery, resulting in a very rapid release of a lot of energy.

As the cell overheats and the energy is released, the internal components within the battery begin to break down, including the flammable electrolyte. It kicks off a sort of incendiary chain reaction that may not stop until the entire battery is consumed. These fires can burn for hours, even re-igniting after they've been extinguished. 

Thankfully, there's a lot of tech in modern batteries to prevent that from happening, including advanced thermal management and huge amounts of crash protection, like the carbon-fiber underbody protection in the electric Mercedes-Benz G-Class, or the aluminum extrusions and cast components that Audi stacks around the cells in the Audi Q8 E-Tron.

Saltwater EV fires

In the wake of hurricane Helene, a video of a Tesla Model X catching fire has been making the rounds. That car was exposed to less than a foot of the storm wake on the western coast of Florida and later caught fire, tragically destroying the home. This isn't the first time this we’ve seen a situation like this. When hurricane Ian cruised through Florida two years ago, there were again EV fires, including another Tesla Model X. 

You can read more details on the problem in our reporting here, but the gist of it is that prolonged exposure to saltwater can breach the battery's protective seals. Shorts can form within the pack, either directly by the conductive saltwater, or by deposited salt after the water recedes. These shorts can then lead to a thermal runaway condition.
EV fire numbers

Okay, let's look into the root of the thing: Are EVs really fire-prone death traps? There have been several studies on the subject, and all come to the same conclusion that electric cars are far, far less likely to combust than cars with internal combustion engines.

One of the more comprehensive studies comes from Sweden's Civil Contingencies Agency (the MSB), which in 2022 cited 23 fires from a pool of 611,000 EVs in service. That compares to 3,400 fires in 4.4 million fuel-burning cars. Do the math, and 0.004 percent of EVs caught fire that year, compared to 0.08 percent of ICE cars. (Note: That study formerly lived here but is sadly offline. An archived version of the study—though not in English—is available here. It has been cited by Top Gear, IEEE Spectrum and The Guardian. All three are great reading if you want to learn more about this topic.) 

EV Fire Safe, an Australian initiative for educating emergency responders about how to work safely around EVs, conducted its own survey and came up with similar numbers. According to that research, between 2010 and 2020, a given EV had a 0.0012-percent chance of catching fire globally. ICE cars, however, had a 0.1-percent chance.

Finally, the Norwegian Defence Research Establishment (FFI) has a study that takes a different tack, looking at insurance claims for vehicle fires. Over the period between 2006 and 2016, EV fires made up just 4.8 percent of overall vehicle fires. Interestingly, that number dropped significantly over the period of study. Looking at data from 2016, 2.3 percent of vehicle fires were due to EVs, seemingly pointing to more recent cars being even safer.

And what about saltwater intrusion? The numbers are somewhat harder to track since it's a rare phenomenon, but according to NHTSA research, of the between 3,000 and 5,000 EVs were at least partially submerged in salt water exposed during hurricane Ian in 2022. 36 EVs caught fire, or less than 0.01 percent. 

New techniques for putting out EV fires
So, that conclusively shows that EV fires are extremely rare, but as explained above, they can be incredibly violent when they do happen. What's the solution? It might require us re-thinking how we extinguish fires. The above video from Cold Cut Systems shows one such technique.

As explained by CTIF, the International Association of Fire and Rescue Services, the video shows a means of penetrating ignited EV batteries and injecting water directly into their internal structure. The result is an EV battery put out in minutes, with only a small fraction of the amount of water that would otherwise be required.