Status-Q

The idea that electric cars are a serious fire risk is one that has established itself in people’s minds, chiefly because such headlines increase advertising revenue for newspaper editors.   If you can’t get a scare story with ‘Elon Musk’ in the title, at least try to include some reference to ‘Tesla’! When a big fire occurred in the car park at Luton airport recently, there were immediate reports suggesting it might have been started by an EV. This was pure speculation, and later, of course, when it turned out to have been a diesel, this wasn’t worthy of any headlines.

Yes, it is the case that EV batteries can catch fire due to thermal runaway, but this is also so rare that there has been very little data on the actual details.  So the Australia-based organisation EV FireSafe has been working to put together some proper statistics, by gathering as much information about EV fires around the world as they can, and their website is a great reference. They also train firefighters on how to deal with such incidents.

First a few basics:

• All cars can catch fire, for a variety of reasons.  EVs are much less likely to do so than other vehicles, though to some degree this is because they are generally newer.
• The difference between EVs and ICE vehicles is that, if the main traction battery is involved in the fire — which is certainly not always the case — the fire will be of a different sort, and generally much harder to extinguish, especially by fire crews who don’t yet have much experience of them.
• It’s very rare that the battery or charging system is the independent cause of a vehicle fire.
• EV batteries tend to burn very hot and for a long time.  They don’t tend to explode.
• You can’t put out such fires with foam, and what you really want to do is just to cool everything down with lots and lots and lots of water. Some fire crews have been nervous about dangers of electrocution from pouring water onto high-voltage batteries, but the risks of this turn out to be exceedingly small and there have been no known incidents with any such problems.
• A few past reports have been dramatically skewed by including e-bikes and e-scooters in a general report on ‘EVs’.  Bikes and scooters have a much higher risk: they are not subject to the same kinds of regulation, there are third-party and counterfeit batteries on the market, batteries are often used after they are dropped or damaged, and so on.  
• Here we are only concerned with cars and other large EVs, and in fires involving the traction battery, which is the thing that distinguishes them from vehicles which carry, say, a tank of highly-flammable liquid instead.

So how common are these fires involving the battery itself?

Well, after gathering as much data as they can about such fires since 2010, they have identified about 400 incidents, from something like 40 million EVs on the road.   They acknowledge that the data is far from complete — they gather what they can from academic surveys, reports by firefighting organisations, and so on — but it’s also better than most other analyses. And it’s worth remembering that a lot of fires involving the battery are not caused by the battery – they’re caused by things like arson, or the car being in a building which caught fire and burned down around it, and so on.

In other words, the risk is tiny.  If you have an e-scooter charging in your garage, you should be more worried about that than the EV sitting on your drive.

If you’d like to know more about the subject, I recommend the Fully Charged podcast episode 244, which has an interview with Emma Sutcliffe of EV Firesafe – available from all good podcast apps, or on the Fully Charged website.