Are electric cars a greater fire hazard than petrol or diesel powered ones?

The images were as dramatic as they were scary. A Tesla Model S, painted in the high-visibility shade of yellow we associate with crash testing, was remotely launched up, over, and off a large ramp, smashing into the ground on the other side. Almost immediately, fire began to swamp the under-side of the car, as the smashed battery pack short-circuited and the dreaded “thermal runaway” began.

Or did it? Actually, no. This was a demonstration organised by AXA Insurance in Germany, and post-test, the company had to somewhat shamefacedly admit that the Model S it used for the demonstration had nothing but empty space where its battery pack would have been. The fire had been faked for the purposes of the demonstration.

AXA’s response? Well of course it was faked. A company spokesperson told The Irish Times that: “It was demonstrated at the event that damage to the underside could potentially also damage the battery and cause a fire. This is a rare but very realistic scenario. However, due to the guests present, a demonstration of a battery fire would have been too dangerous. The battery cells of the electric car were therefore removed before the test. As in the AXA crash tests in previous decades, the vehicles were propelled by a pulley system using a tow vehicle.”

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The test was part of a regular series of crash experiments carried out by AXA to help it better understand how and why cars crash, and therefore how much it can then charge us all for our insurance premiums. “The risk of fires is fortunately low for cars, irrespective of whether they are powered by petrol or electricity. Statistics show that only five out of 10,000 cars fall victim to fire. Vehicle fires in electric vehicles can, however, be extremely tricky for the emergency services due to ‘thermal runaways’, ie the battery cells burning.

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“The accident researchers wanted to draw attention to this, so a fire was simulated on site. This was all communicated transparently at the event and discussed with experts during a podium discussion,” said the spokesperson. “Tesla was chosen for this accident simulation because the make is popular and representative of high-performance electric cars. Later at the event, it was also emphasised that current Tesla models are equipped with additional reinforcement of the underside, which our accident researchers welcomed from a safety perspective.”

The underbody seems to be the Achilles heel of electric cars because the battery is not additionally protected there. Motorists should be aware of this

—  Michael Pfäffli, AXA

However, according to Michael Pfäffli, AXA’s head of accident research, not all EVs are equal in this regard, and the underside of the battery pack is a potential Achilles heel for many. “Investigations by AXA accident researchers have shown that underbody damage can occur when crossing street islands, stones or even spinning tops. Although the drive battery is very well protected by additional stiffeners of the body front, rear and side, it has a weak point,” he said. “The underbody seems to be the Achilles heel of electric cars because the battery is not additionally protected there. Motorists should be aware of this.”

That would make it seem as if an electric car’s battery pack is simply a blaze-in-waiting, hovering in the wings for that moment when you drive over a grain of gravel and – ping – there’s a hole in your battery and the whole thing is about to “whumpf” up in flames.

That’s simply not the case, though. The problem is that electric cars are relatively new technology, and so any incident which involves one – especially a runaway fire – garners headlines. The statistics currently show that, actually, EVs are generally less likely to be involved in a fire-related incident than a conventional petrol or diesel model, or even a hybrid.

According to the Swedish Myndigheten för Samhällsskydd och Beredskap (MSB, or Authority for Social Protection and Preparedness), 29 EVs and 52 hybrids caught fire in Sweden between 2018 and 2022. The average number of fires each year involving electric vehicles in Sweden stands at 16, a figure grouping hybrids and full battery EVs together. In total, about 3,400 passenger vehicles catch fire each year in Sweden, which means that a mere 0.4 per cent of all passenger vehicle fires there annually involve an electric or electrified car.

“Statistically, the threat of fire from an EV seems to be less than that from an internal combustion-engined vehicle,” Paul Logan, health and safety operations manager at Peninsula, a company which specialises in safety and risk assessment, told The Irish Times. “It’s not necessary to only park electric vehicles outside, although lithium-ion car batteries experiencing thermal runaway will burn somewhat differently from a fire involving a diesel or petrol vehicle. Studies by The Danish Institute of Fire and Security Technology have both determined that EV car fires are largely fuelled by the car parts and interiors made from plastic materials and that fire loading is similar to that of diesel or petrol vehicles.”

Logan went on to point out that we’re still in the early days of dealing with and becoming accustomed to electric vehicles, and that much of the risk of fire – in any car – can be alleviated through simple regular maintenance. “Most evidence to date suggests that fires in EVs are less likely to occur than in hybrid vehicles and petrol or diesel vehicles.

The likes of Tesla and others are switching to lithium-iron phosphate, or LFP, batteries, which have a much lower risk of fire

—  Paul Logan, Peninsula

Thatcham Research, the UK motor insurers’ research centre, used the data to calculate the percentage of fires per year per average number of cars of a particular propulsion type for the years 2018-2020. This analysis showed that the average percentage of fire claims per year for an EV is just 0.001 per cent, and 0.003 per cent for both plug-in hybrid vehicles and REEVs. This is lower than 0.007 per cent for petrol vehicles and 0.011 per cent for diesel vehicles. “In effect diesel vehicles are 11 times more likely to catch fire,” said Logan.

“However, fire risk may increase as cars and charging facilities age, so this will need to be monitored. As with any electrical appliance, damaged charging stations or cables will increase the fire risk, so should be avoided wherever possible. While the technology is pretty new, equally some of it is changing already. The likes of Tesla and others are switching to lithium-iron phosphate, or LFP, batteries, which have a much lower risk of fire.”

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In fact, Logan points out that there is currently a much greater risk from battery fires started by company e-bikes and e-scooters, as not only are these more prone to damage, they are also more likely to be stored inside your house.

Nonetheless, there are concerns. Recent videos have shown electric vehicles being recovered from cargo ship the Fremantle Highway, which had drifted ablaze in the North Sea for a week. While the cause of the blaze is still being established, salvage crews were seen dunking electric vehicles taken from the hold into giant skips full of water, just in case they burst anew into flames. That is one of the less-than-rosy aspects of electric vehicle fires – even when doused, and it can take as much as 30,000 litres of water to douse them, the damaged battery cells can short-circuit again and reignite the fire.

Thankfully, there are better solutions than requiring a whole swimming pool’s worth of water for a burning EV. Vehicle Fire Blankets, based in Scotstown in Co Monaghan, imports Bridgehill fire blankets. These are not your usual damp-tea-towel-over-a-chip-pan affairs, but are large, exceptionally heavy (two people at least to lift one) blankets impregnated with quartz.

Drape one of these over a burning EV, and not only does it cut off the flow of oxygen to the fire, but it also contains the smoke – which can be toxic, depending on how much of the car is ablaze. “The Bridgehill fire blanket can be used on critical failure response to battery cell punctures, ruptures, or accident damage. It will immediately reduce smoke and has the ability to reduce heat quickly while removing available oxygen to the thermal runaway. You can then isolate and quarantine the vehicle,” David Smyth from Vehicle Fire Blankets told The Irish Times. “It’s getting to where this is standard equipment for car dealers in Norway, where they have to have the ability to repair high-voltage batteries on-site. They’ve also been fitted to European Parliament buildings.”

It’s worth remembering that there have been two catastrophic vehicle fires in Ireland in recent years. The largest, and most costly (although thankfully not at the cost of human life), was the fire in a multistorey shopping centre car park in Douglas, on the outskirts of Cork City, which saw €30 million in damage caused, and a year-long repair and reconstruction job. More recently, a car fire in a drive-through lane at a McDonald’s in Newbridge, Co Kildare, saw the restaurant gutted by the flames, although again thankfully with no one seriously hurt. In both of these cases, the cars that started the fires were petrol-powered, not electric.

That doesn’t mean we have nothing to fear from electric car fires – clearly, there’s always going to be a risk, and we need to learn how to cope with those risks and train our emergency services in how best to deal with them – but right now, and at least until electric cars gain primacy in the market, those risks are pretty well vanishingly low.

Just don’t be surprised to see increasing insurance premiums for electric cars amid all of this. Going back to that faked AXA EV fire, the insurance company took the opportunity to point out that EVs need better battery protection, and that dealing with any fires is going to be more costly. “If damage to the battery occurs, immense fires can quickly occur. If there is only a risk that the battery could ignite, the vehicle will be stored in the extinguishing container for days. The fact that we all still have a way to go can be seen, for example, in the fact that there are not yet many firefighting containers and these cars sometimes have to be stored in closed parking lots,” says Nils Reichweiter, AXA’s head of property insurance.