Why do electric cars burn?

Often highly publicized for their impressive visuals, electrical car fires are fortunately extremely rare. But why can an electric car catch fire and why is fire so persistent? Answer in this article.

Car fires are, in most cases, intentional, but sometimes they can be accidental and due to malfunction. Often after a fire, when the car is new, the manufacturer investigates whether the fire was caused by a manufacturing defect and organizes a recall campaign.

In recent years, the emergence of the electric car and the numerous questions revolving around a technology that happens to be relatively “new” compared to thermal cars, events and especially fires related to them, have been making headlines in specialized magazines. press We can cite the example of a car fire in the Gironde in the summer of 2022, which was caused by an electrical fault in a thermal van! Or even a Hyundai Kona with a seemingly faulty battery.

There are many articles highlighting one or another electric car (mostly Tesla, because they have been “alone” in the electric car market for a long time and are numerous) in the grip of fire.

As a result, in the collective imagination, and this is quite normal, we regularly hear it said incorrectly ” an electric car is more likely to catch fire than a thermal car“. To make matters worse, Given the high energy density of lithium-ion batteries, these fires are often effective and violent.. This leads to a long and persistent fire, thus forcing firefighters to deal with stubborn and spectacular fires. Below, for example, is a Tesla Model S that catches fire, and it has nothing to do with a thermal car.

How does a fire happen in an electric car?

There can be many causes of fire for a thermal car. In most cases, this happens after a road accident, with manufacturing defects and poor maintenance coming in second and third, respectively. This can lead to a fuel leak, electrical system failure, significant heat source (engine overheating, etc.), catalytic converter problem, etc.

As you surely know, electric cars are technically less complex than thermal cars (absence of many fluids, complex gearboxes, flammable elements, etc.), so they should be less prone to fire. But we will return to this topic a little later.

However, what could cause an electric car to catch fire? As with thermal models, the causes can be many, but they are usually very different. Damaged electrical wiring and batteries are usually the most exposed elements that cause fires in an electric vehicle.. Since 100% electric cars are, for the most part, very new, these concerns do not yet apply to them.

The most common risks in a new car are related to batteries, especially often related to it overload and high temperature. But there again, these are mostly manufacturing defects where overload and high temperature are only aggravating factors. Most battery failures are caused by suppliers, not manufacturers.

Determining the source of a thermal or electrical fire is usually very difficult, as the car is usually completely burnt and the traces of the origin of the fire are lost.

Why are fires so stubborn?

What accounts for the media coverage of these fires is really the “novelty” effect of the electric car, but also the presence of some very dangerous groups who hate the electric car and take the opportunity to make light of this type of problem. But the main reason for this media coverage is because of that these fires are sudden, stubborn and very impressive.

Some even compare the combustion of electric cars to gas-powered ones. Recently, a video of an electric bus burning in Paris went viral. especially since the pictures were quite impressive. Electric car lights are very complicated for firefighters because these models are their own fuel source, they can burn for hours and are difficult to cool down.

So even though the fire appears to be out, can light up quickly, and therefore firefighters are now trained to extinguish fires involving battery-powered (hybrid and electric) vehicles. A few years ago, Tesla even produced a guide designed for first aid attention. In the same spirit, General Motors has organized first aid training in the event of an electric vehicle fire in Canada and the United States.

A new challenge for firefighters

Electric cars do not burn like thermal cars. Here’s what firefighters noted after a Tesla Model S caught fire on the Sacramento side a while ago: 17,000 liters of water were needed to put out the fire, and a mini basin was created to submerge the electric batteries. In its report, Tesla indicates that this is generally necessary Between 11,350 liters and 30,300 liters of water to put out an electric car fire.

Batteries can also catch fire again hours or even days after the initial event, due to a phenomenon known as “thermal runaway” that can occur in damaged lithium-ion batteries. Also, according to the American manufacturer, it is recommended to monitor the temperature of the batteries for at least 24 hours after the fire.

Manufacturers are now required to publish a first aid manual for every model they make, but the US Transportation Accident Investigation Board (NTSB) recently clarified that Of the 22 relevant manufacturers, only eight fully incorporated its recommendations.

Do electric cars burn more than others?

As we mentioned above, with the information in the press about electric cars on fire, one would think that they are more prone to fire. But what about the facts? It’s hard to take a step back because the electric car is still new, but a recent American study is overturning the accepted view.

In fact, the insurer Insure yourself collected several thousand data from three different sources to develop an assessment of the vehicles most at risk. The three sources in question are the NTSB, the Bureau of Transportation Statistics, and the US Central Registry of Vehicle Recalls.

And the data is quite edifying, because after the insurer cross-checks official registration data with the number of fires recorded by the department, whether accidents or “spontaneous” fires, The vehicle category most vulnerable to fires will be hybrids. The insurer also highlights a fire rate of 3,457 per 100,000 vehicles, ahead of heating (1,529) and electricity (25). This is not an absolute value (because 3.457% of hybrid cars will burn, which would be a lot…), but the rate of fire.

In general, in the event of a fire risk, manufacturers are very reactive and set up fairly significant recall campaigns. For example, Hyundai recently had to recall 82,000 Kona electric cars due to battery problems.

It recently made headlines in the US with the Chevrolet Bolt. Chevrolet’s parent company, General Motors, advised owners of some Bolt EVs in mid-2021 not to leave their vehicles indoors or charge them unattended overnight before starting the recall. After investigation, defects in batteries manufactured by LG may cause fire in certain cases.

The French insurance company AXA confirms the information based on accident figures: an electric car is no more likely to catch fire than a thermal car (gasoline or diesel).

On May 22, 2022, a Tesla Model Y spontaneously combusted. Its occupant panicked and broke a window to get out. We wondered why electric car fires happen like this…
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