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tl;dr: Don’t Ever Set Your Electric Car on Fire

What happens to lithium ion batteries and how to put them out

This is a true story. Although it's not directly about artificial intelligence, it does concern electric vehicles (EVs), which are a significant part of the broader AI discourse.

Soon, more and more EV cars will inhabit the cities. Knowing more about them – from all perspectives – is crucial. And today's story is about an EV on fire.

This post is part of the Premium membership: as we announced before, paid subscribers can submit their posts to be published on Turing Post. Please upgrade (if you haven’t yet) and send us your stories. Everything from the modern tech world will be considered.

This post was submitted by Will Schenk, co-founder of the TezLab app.

The Fire

Ours was the first double Tesla fire in Litchfield County, Connecticut — the first single Tesla fire for that matter! Our barn caught fire on Thursday night, May 18th, 2023. The fire started somewhere between the generator and the two large propane tanks and quickly spread through the entire building. The barn was a mismatch of colonial building and owner constructions over the decades. No one was sure when the original part was built, but it was most likely in the mid to late 1700s. The old wood was very dry, and it went up quickly. The propane tanks certainly didn’t help. But they lit the trees around the barn.

The heat was too much for the two Tesla Model Xs charging just outside. When we saw the barn ablaze, the cars were still untouched by fire. But that was a matter of minutes.

We raised the alarm, and they called in the Strike Team. Six different crews arrived on the scene to help figure out how to save the house. The propane tanks were big and dangerous but somewhat familiar. But the electric cars put a whole other spin on it.

Let’s take a look at what they had to deal with, how they are learning different techniques and skills, and how that knowledge is getting out to that important segment of society that helps out when things go sideways.

Lithium Ion Batteries

Batteries behave differently at different temperatures. As all EV drivers know, when your battery is cold, you just don’t have the same range as when it’s at ideal temperatures. Below 20°F (-6°C), my Tesla went only about 40% of the distance it would have at 72°F (22°C). But overheating is really the bigger problem.

Around 140°F (60°C), things start to get really bad. Big EV batteries all have cooling systems. If you want to nerd out on all the science, I’d recommend 'A review of thermal runaway prevention and mitigation strategies for lithium-ion batteries’. But here’s the payoff image:

Source: ScienceDirect

When you discharge energy from the battery, it heats up. Normally, the cooling system will keep the cells in their working temperature. As it goes hotter, the batteries themselves start to physically degrade, and you move into Stage II where the cells themselves begin to be physically damaged and will start venting. As you move into Stage III, you enter what’s called a 'thermal runway', where the chemical reactions inside the battery are releasing enough heat to cause more reactions, and the batteries are breaking down, venting gas, and in general exploding.

At this point, all you can really do is watch it go and hope that it’s not close to anything else.

The truth of the matter is there is no simple solution or tool to stop a thermal runaway in an EV’s high-voltage battery. Directly cooling the battery cells is the best method, however the manufacturers do not give first responders direct access to the inside of the battery box. Trying to cool the battery cells from the outside will only extend a crew's time on scene.

If the battery box is intact and there are no exposures, the best solution is to simply wait for the battery to burn itself out, then extinguish the remaining class A fire. While this strategy is not ideal – and not one favored by aggressive, proactive and eager firefighters – it’s really the best approach. It should only take an hour for the battery to burn itself out. The alternative will be to continually dump water on the vehicle for 6 to 8 hours.

Patrick Durham at FireRescue1 

Burning Cars

The heat from the barn set the cars on fire. At first, there was smoke coming off the side, and then they started burning. We were far away (as you might imagine), and we weren’t thinking about cinematography at the moment, but there are a couple of shots we did take.

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Once they started to go, there were fireworks. The color of the burn is mostly what you’d expect: that glowing orange color you recognize from regular wood fires. Occasionally, though, there would be flashes of white light, sort of like fireworks or larger sparklers. The thought was that it was magnesium combusting, but there seemed to be a lot of chemically charged stuff in there. There were popping and exploding noises, which were the battery cells overheating and exploding. Thermal Runaway is a hissing sound; it sounds like lots of pressure is trying to escape, punctuated with occasional popping explosions.

There were two hoses on both of the cars for around 45 minutes, which, they said, was roughly 300 gallons per minute each. This is a lot of water going down my driveway and into the wetlands! They managed to get both of them out, but the 2023 Model X kept reigniting. Around this time, the blanket arrived.

They used a Bridgehill Blanket, and when they put it on, there were flames coming sideways out of the vehicle. Later, after it was extinguished, I found parts of the Tesla that had shot a fair distance away. Once the blanket was on the car, the water was more effective both in putting out the fire and keeping it out.

The owner of the blanket, who owns a towing company, told me that he keeps one in all of his trucks as a preemptive measure, but this was the first time they've used it. His concern was that one day there would be an EV that he'd need to tow, and he planned to use it after it got back to his lot to protect the buildings and other cars nearby. He’d heard about what happens to EVs from the NTSB report but had never had experience with it. Honestly, I think he was very curious to see how and if it actually worked in practice.

The Timeline

  • 9:55 – one of the kids woke everyone up screaming: “FIRE!”

  • 10:00 – we called 911, after getting everyone out of their beds (there were four kids and three adults in the house that day).

  • 10:06 – the first responders showed up. The barn was completely on fire and the smoke was coming off the Teslas.

  • 10:09 – both Teslas were “Fully Involved.”

  • 10:12– the Strike Team was called in.

  • 10:36 – someone with an “EV Blanket” was on the way.

  • 11:00 – the blanket was deployed. The 2018 Model X was already out at this point, but the 2023 Model X seemed to be trickier and the blanket was used on that.

  • 11:52 – it was all over and people were starting to go home.

The EVs were ashy skeletons, and the area where the water washed down the driveway smelled pretty gross. Not only did we lose the energy stored to power the car, but the storage system itself was destroyed, and it didn’t seem right at all. The batteries are meant to store and discharge energy, not be reduced to a pile of chemical ash. Generally, it’s all icky, and I wanted to scrape off the top layer of gravel and test the well water, just in case.

Moving the cars

What the hell is that? They told me there was a burn down, but this is just a pile of ashes! I can’t take that.

The first towing company the insurance people sent looked at it then turned around and left. I guess in towing lingo, a ‘burn down’ means something different for an Internal Combustion Engine (ICE) car. Maybe there’s more of the structure left? They still have wheels or attached axles?

The second guy was a bit more resourceful. I sent pictures of everything to the dispatcher when they called to schedule a driver. “I guess we could send a flatbed truck but maybe you need something with a bit more… containment?”

This video is slow and long but just to give you a sense of the experience and him trying to figure out what he could attach the cabling to.

The third guy who came for the second car needed a bit more help: I had to push the carcass up onto the flatbed using the tractor!

The main concern these guys had, and it’s a very good thing to be concerned about, is all of the ashes flying off the car in the wind as they drove. We came upon the solution of using a fire blanket to wrap the car, which seemed like the best out of a list of terrible options. I found out later that it was the official recommendation. He needed help maneuvering it on, and it was clearly the first time that this particular company ever had to deal with this problem.

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All in all, we were incredibly lucky, no one was hurt, and the house was spared.

But lithium-ion batteries are a bit of a nightmare for firefighters. In addition to the huge car batteries, the fire inspector team was very interested in every other battery I had in the barn, which included 56V batteries for lawn equipment, tons of things for hand power tools, and an electric bicycle. They wanted to know brand names and the placement for each. There’s no good way to put them out, and when they get old, short, or who knows what, there’s a lot of energy in there, both electrical and embodied, that can cause harm.

Knowledge on how to deal with these fires isn’t really that effective, and it’s slowly moving through the community as they develop better ways to deal with it. Everyone is trying to be as proactive as they can, but there’s not a whole lot to do. Better safety systems probably need to be developed and put into place — something equivalent to the pressure release valves on propane tanks.

There will need to be a better system for towing, storage, and disposal of damaged electric vehicles, and that knowledge will need to get out to all of the local guys who get called in. ICE cars have a huge infrastructure in place with gas stations, body shops, service stations, and wrecking yards, and EV cars need to develop the same. We are focusing on charging now, rethinking the convenience store and rest areas, but as more cars are out there, we need to help adapt the existing emergency and service community to absorb this new spin on all these life challenges.

RIP Chess Chess and Phoenix Noir

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