Why Teslas keep catching on fire

Glenn Harvey for Vox

EVs catch fire far less often than gas-powered cars, but firefighters still need to adapt.

When Thayer Smith, a firefighter in Austin, Texas, received the call that a Tesla was on fire, he knew that he’d need to bring backup.

It was in the early morning hours of August 12, 2021, and a driver had slammed a Model X into a traffic light on a quiet residential street in Austin before crashing into a gas pump at a nearby Shell station. The driver, a teenager who was later arrested for driving while intoxicated, managed to escape the car, but the Tesla burst into flames. As emergency responders battled the fire in the dark of night, bursts of sparks shot out of the totaled car, sending plumes of smoke up into the sky. It took tens of thousands of gallons of water, multiple fire engines, and more than 45 minutes to finally extinguish the blaze.

“People have probably seen vehicles burning on the side of the road at one point or another,” Smith, the division chief at the Austin Fire Department, recalled. “Just imagine that magnified a couple times because of all the fuel load from the battery pack itself. The fact that it won’t go out immediately just makes it a little more spectacular to watch.”

Like other Tesla fires, the fiery scene in Austin can be tied to the Model X’s high-voltage battery. In Austin, the electric vehicle ignited after a slide across the base of a traffic pole that the driver had knocked down caused the battery on the bottom of the car to rupture. At that point, the impact likely damaged one or several of the tiny cells that power the car’s battery, triggering a chain of chemical reactions that continued to light new flames. Though firefighters were able to put out the fire at the gas station, what remained of the car — little more than a burnt metal frame — reignited at a junkyard just a few hours later.

The Austin crash led to a lot of headlines, but EV fires are relatively rare. Smith said his department has seen just a handful of EV fires. While the US government doesn’t track the number of EV fires, specifically, Tesla’s reported numbers are far lower than the rate for highway fires overall, the National Fire Protection Association (NFPA) told Vox. The overwhelming majority of car fires are caused by traditional internal combustion vehicles. (This makes sense, in part because these vehicles carry highly flammable liquids like gasoline in their tanks, and, as their name implies, their engines work by igniting that fuel.)

Still, people have started associating EVs with dramatic fires for a few reasons. Videos of EV fires like the one in Austin tend to go viral, often attracting comments that condemn President Joe Biden and the electrification movement. At the same time, misleading posts about EVs spontaneously exploding, or starting fires that can’t be put out with water, have helped promote the narrative that electric vehicles are far less safe than conventional cars. The research doesn’t bear this out. Two recent Highway Loss Data Institute reports found that EVs posed no additional risk for non-crash fires, and the NFPA told Vox that from a fire safety perspective, EVs are no more dangerous than internal combustion cars.

This narrative has another nefarious side effect: It stands to distract from a more complicated EV fire problem. Although they’re relatively rare, electric car fires present a new technical and safety challenge for fire departments. These fires burn at much higher temperatures and require a lot more water to fight than conventional car fires. There also isn’t an established consensus on the best firefighting strategies for EVs, experts told Vox. Instead, there’s a hodgepodge of guidance shared among fire departments, associations that advise firefighters, and automakers. As many as half of the 1.2 million firefighters in the US might not be currently trained to combat EV fires, according to the NFPA.

“The Fire Service has had 100 years to train and to understand how to deal with internal combustion engine fires,” remarked Andrew Klock of the NFPA, which offers EV classes for firefighters. “With electric vehicles, they don’t have as much training and knowledge. They really need to be trained.”

The stakes are incredibly high. If the White House has its way, electric vehicles will go mainstream over the coming decade. An executive order signed by President Biden calls for 50 percent of new car sales to be electric by 2030, and the administration is pouring billions into building EV infrastructure and battery factories across the country on the assumption that people will buy these cars. EV fires — and misinformation about them — could stand in the way of that goal.

How an EV fire starts

An electric vehicle battery pack is made up of thousands of smaller lithium-ion cells. A single cell might look like a pouch or cylinder, and is filled with the chemical components that enable the battery to store energy: an anode, a cathode, and a liquid electrolyte. The cells are assembled into a battery pack that’s encased in extremely strong material, like titanium, and that battery pack is normally bolted to the vehicle’s undercarriage. The idea is to make the battery almost impossible to access and, ideally, to protect it during even the nastiest of collisions.

Things don’t always go as planned. When an EV battery is defective or damaged — or just internally fails — one or more lithium-ion cells can short-circuit, heating up the battery. At that point, the tiny membranes that separate the cathode and the anode melt, exposing the highly flammable liquid electrolyte. Once a fire ignites, heat can spread to even more cells, triggering a phenomenon called thermal runaway, firefighters told Vox. When this happens, flames continue igniting throughout the battery, fueling a fire that can last for hours.

The first moments of an EV fire might appear relatively calm, with only smoke emanating from underneath the vehicle. But as thermal runaway takes hold, bright orange flames can quickly engulf an entire car. And because EV batteries are packed with an incredible amount of stored energy, one of these fires can get as hot as nearly 5,000 degrees Fahrenheit. Even when the fire appears to be over, latent heat may still be spreading within the cells of the battery, creating the risk that the vehicle could ignite several days later. One firefighter compared the challenge to a trick birthday candle that reignites after blowing it out.

Because EV fires are different, EV firefighting presents new problems. Firefighters often try to suppress car fires by, essentially, suffocating them. They might use foam extinguishers filled with substances like carbon dioxide that can draw away oxygen, or use a fire blanket that’s designed to smother flames. But because EV fires aren’t fueled by oxygen from the air, this approach doesn’t work. Instead, firefighters have to use lots and lots of water to cool down the battery. This is particularly complex when EV fires occur far from a hydrant, or if a local fire department only has a limited number of engines. Saltwater, which is extremely efficient at conducting electricity, can make the situation even worse.

Michael O’Brian, a firefighter in Michigan who serves on the stored-energy committee for the International Association of Fire Chiefs, suggested that sometimes the best strategy is to simply monitor the fire and let it burn. As with all car fires, he says his priority isn’t to salvage the vehicle.

“Our fire service in general across the United States [and] in North America is understaffed and overtaxed,” O’Brian explained. “If you’re going to commit a unit to a vehicle fire for two hours, that’s complicating.”

Some EV batteries can make this problem worse. In 2021, the National Highway Traffic Safety Administration and General Motors announced an expanded recall of all the Chevy Bolts the car company had manufactured because tiny components inside some of the Bolt batteries’ cells were folded or torn. Chrysler issued a recall in 2022 after an internal investigation found that the vehicles had been involved in a dozen fires. Chrysler has yet to reveal the root cause of its battery issue and told Vox it’s still investigating. The company’s temporary solution was a software update that monitors when the car’s internal sensors determine that the battery might be at risk of igniting.

Tesla’s vehicles have their own set of problems. Tesla cars have retractable exterior door handles that only extend electronically, and only when the car has power. An emergency response guide for the 2016 Model S says that if exterior door handles aren’t working, there’s a button on the inside of the vehicle that drivers can use to open the car manually. Yet some allege that this feature makes it more difficult for emergency responders dealing with a Tesla fire. A lawsuit filed by the family of Omar Awan, a Florida doctor who died in 2019 after his Model S crashed and burst into flames, said that a police officer who arrived on the scene couldn’t open the doors from the outside.

Similarly, in a YouTube video that captured a recent Tesla battery fire in Vancouver, an owner recounts having to smash open the car’s windows because the electronics stopped working and the doors wouldn’t open. “I could feel it in my lungs, man,” he says on the recording. Tesla has also faced several other lawsuits alleging that its battery systems are dangerous. The company, which does not have a PR department, did not respond to a request for comment.

Experts Vox spoke to, including firefighters as well as fire safety officials, say that while Teslas are the most common electric cars on the road right now, EV firefighting goes far beyond any one carmaker. Perhaps the biggest challenge of all is that as EVs go mainstream, EV fires aren’t being studied as much as experts and government officials say they should be. “The unfortunate part is that we’re not really moving this as quickly as we should and updating it,” Lorie Moore-Merrell, the US fire administrator at the Federal Emergency Management Agency (FEMA), told Vox.

The national fire incident tracking system currently used by FEMA was invented in 1976 and was last updated in 2002, so it doesn’t specifically track electric vehicle fires. While the agency does plan to update the system with a new cloud platform, FEMA said it will only start building the technology later this spring, and then it will transition from the legacy system sometime in the late fall.

Firefighting in the electric era

Amid a barrage of news reports about the Model X fire in Austin last year, Tesla reached out to the city’s fire department. Michael McConnell, an emergency response technical lead at Tesla, first spoke with Smith, the division chief, on the phone and later sent him an email, which Vox obtained through a public records request, with advice on how the fire department might approach the same situation in the future.

“First of all, let’s debunk the myth of getting electrocuted. Lots of things have to go wrong in order for that to happen,” Smith said. “If the battery pack has not been compromised, then just leave it alone.”

In the long, wide-ranging message, McConnell also explained what assistance Tesla could and could not provide. He offered online training sessions but could not arrange in-person training because, McConnell explained, he had “just too many requests.” A diagram for the Model X implied there was magnesium in a part of the car that did not, in fact, contain magnesium. There was no extrication video guide for the company’s Model Y car (extrication is the firefighter term for removing someone from a totaled vehicle). It would be difficult to get a training vehicle for the Austin firefighters to practice with, McConnell added, since Tesla is a “build to order manufacturer.” Most of Tesla’s scrap vehicles are recycled at the company’s Fremont plant, he said, though a car could become available if one of Tesla’s engineering or fleet vehicles crashed.

McConnell’s long email reflects the current approach to fighting EV fires and the fact that fire departments across the country are still learning best practices. Even now, there isn’t consensus on the best approach. Some firefighters have considered using cranes to lift flaming EVs into giant tanks of water, although some automakers discourage submerging entire vehicles. Rosenbauer, a major fire engine and firefighting equipment manufacturer, has designed a new nozzle that pierces through the battery casing and squirts water directly onto the damaged cells, despite some official automaker guides that say firefighters shouldn’t try rupturing the battery. Another factor that needs to be considered, added Alfie Green, the chief of training at the Detroit Fire Department, is that there are new car models released every year, and there is particular guidance on how to disconnect different cars.

While some standards have been released, others are still being developed, and fire departments are still catching up with National Transportation Safety Board recommendations. There’s also the matter of just getting the vast number of firefighters up to speed on EVs. O’Brian, the fire chief from Michigan, told Vox that the federal government needs to take a much more active role in funding research and helping buy EVs that fire departments can practice on.

Another complication is that EV fires present different risks in different places. The New York City Fire Department (FDNY) hasn’t had to fight any electric car fires yet, but it is facing e-scooter and e-bike fires, which are on track to double compared to last year and disproportionately endanger delivery workers in the city. Batteries that lack safety certifications or are charged improperly are more likely to ignite, explains John Esposito, the FDNY’s chief of operations. In November, 43 people were injured in a Manhattan building fire that the department ultimately linked to a battery-powered micromobility device — possibly a scooter — that had been kept inside an apartment.

Small towns face unique hurdles. In Irmo, South Carolina, which is home to fewer than 12,000 people, there’s concern about getting the right equipment to deal with EV fires. While there haven’t been any high-voltage battery fires yet, Sloane Valentino, the assistant chief of Irmo’s fire department, told Vox he’s not sure whether the town has enough engines to fight a Tesla fire while also responding to other fires in the area.

“We don’t have the capacity to deal with 30,000 gallons worth of toxic runoff. Some of it’s going to turn to steam,” Valentino told Vox. “We’re kind of back to, ‘Let it burn.’ When you see the big, violent flames shooting out of the car, just kind of protect what you can — try to cool the roadway — but let the car burn.”

Engineering a safer future

While internal combustion vehicles have been around for over a century, EVs are still relatively new, which means they could become even safer as more money and research pour into the technology. Remember the melting separator in the battery that creates thermal runaway? General Motors is studying how its battery separator could contribute to improved battery safety. The Department of Energy is working on technology that could incorporate flame retardants directly into the batteries’ design. Engineers are also investigating new battery chemistries, like less-flammable electrolytes. Though research is still early, solid-state batteries, which would replace a liquid electrolyte with a solid that’s far less likely to ignite, also show promise.

“Batteries are hopefully going to be getting better over time,” said Michael Brooks, from the Center for Auto Safety. New regulation could push battery safety even further, he added.

In the meantime, fire departments are working on adjusting to this new category of fire — just another reminder that the rise of electric vehicles involves far more than simply replacing gas tanks with batteries. And firefighters will be the ones driving some of these new EVs. In May, the Los Angeles Fire Department debuted the first electric fire truck to hit the road in the US. The bright red engine is made by Rosenbauer, and it comes with a front touchscreen, a remote control tablet, two onboard batteries, and a backup diesel range extender. Other departments are now waiting for their own EV fire trucks to arrive.

Meanwhile, back at the Austin Fire Department, Smith says he has encountered at least one EV fire since the Model X accident a year and a half ago. That one didn’t involve the battery, so it was like fighting any other car fire. But in the months following the 2021 crash, the fire department did go ahead and jury-rig a new firefighting nozzle to deal specifically with EV fires. The department hasn’t heard anything more from Tesla.

Rebecca Heilweil is a reporter at Vox covering emerging technology, artificial intelligence, and the supply chain.

You May Also Like