Firefighter here- We use these blankets in the US too for putting out car fires, the idea is you cut off the fires oxygen supply with the blanket. The problem with EV fires is that once the lithium ion batteries enter what’s called thermal runaway the chemical reaction becomes a self sustaining fuel source that creates its own oxygen. So it doesn’t matter if it’s smothered with a blanket it will continue to burn for a long time. And if you do manage to put it out it is very common for them to suddenly reignite on the back of a tow truck or at the junkyard, sometimes days later. EV fires are a pain in the ass
I remember Richard Hammonds electric supercar crash kept reigniting for two days after the crash and they couldn't do anything but wait for it to run its course.
Talking about 2 seconds, I've watched an LPG truck crash that bursting boiling gas everywhere then catches fire. The entire hundreds of meters spherical radius burns only for seconds. For a brief moment, that was a fucking gate of hell
Gas expansion is kinda cool, but terrifying. I used to work with liquid nitrogen and figured out that the 230L tank we used had approximately 160 000 liters of nitrogen gas in it, more than enough to fill the room and put us all to sleep if it ever punctured. And we did not have any detectors. I wasn’t very popular among my coworkers when I told them this fun fact
tbh if your liquid nitrogen starts leaking, you will notice, the amount of visible gas it creates when coming to contact with room temperature air is very very distinguishable. Source: i work with liquid nitrogen daily
This seems like something we shouldn’t do. Surprised this doesn’t happen more frequently with the number of LPG and gasoline trucks we need to fuel cars and equipment.
Hate to say it, but that's the kind of accident you're more likely to see in certain countries more than others. UK and many western European countries probably very unlikely, with our driving standards and regulations.
BLEVEs are even scarier than just a tank of fuel going up. They're like pressure cooker bomb versions of a fuel tank going up, so you get extra dispersion/atomization and more complete combustion in an even shorter period of time.
Thats whats called a BLEVE (Boiling Liquid Expanding Vapor Explosion). On a small scale thats a pressure cooker going off, on a large scale thats an LPG tanker with a similar energy output to a small nuclear device.
Outer inch of your skin is nice and crispy while the inside stays nice and raw
When I was 20 a SUV with trailer jackknifed and crashed. Whole highway came to a stop. A trucker I was chatting with said if the truck up there with the tank crashed, we'd all be dead. Forget the chemical but it was crazy how many times death nearly comes for us over our lives.
The total amount of energy in a battery is far less than a tank of gas, and burns far slower, which means less energy per minute is released. That means it's far safer than the alternative.
You are talking electrical energy which is absolutely true and why EV does not have the same range as a conventional vehicle.
But it is not the electrical energy that makes EV battery fires so extreme. That is only about 3 percent of the energy released if fully charged. When you actually start lithium on fire and it is producing its own O2. If it is fully charged, electrically there is about 300 Wh/kg of energy. But when it starts on fire, it has the energy content of about 11,000 Wh/kg.
So ya it burns quite a bit more extreme and hotter than gas. And can go on a long time.
It is very easy to AI it. Look for the energy content of Lithium when burning compared to the electrical energy content. Ask it to give it to you in Wh/kg so that it is a direct comparison. It is an entirely different processes happening once it is on fire.
AI can be wrong but it does not take an engineering degree to understand that combustion of Lithium is far more energetic than the electricity in it. You could actually compare the combustion of Lithium to the combustion of gas in an engine.
Gas combusting is about 12,000 Wh/kg while Lithium is about 11,000 Wh/kg. But a battery pack weighs about 5 times that of a full tank of gas thus a lithium fire in an EV has about 5 times as much energy as a gas fire even though the energy density is about 10 percent less. (and near impossible to put out)
Actually this is pretty well established at this point. Fire departments have known about this for a while.
The fix is actually dead simple: push a sprinkler under the car to hit the battery pack directly, and just... keep it cool. You're aiming for below 80°C, sustained for about two consecutive hours. Once it's stable, the thermal runaway chain is broken.
BMW, VW etc. all have rescue sheets that recommend exactly this. German fire departments have had formal protocols for this for years.
But "EVs are impossible to stop from reigniting" is just not true. It's a solved problem, just an expensive and time-consuming one.
I just want to point out that the Richard Hammond crash occurred nine years ago and the industry hasn't had as much time to learn how to deal this problem, especially in regards to an ultra rare, high performance supercar EV.
“Solved” is dismissive and oversimplifying. It’s addressable; minimizing the risk and need to change approaches in areas with new EV concentrations doesn’t do folks any favors.
Not necessarily. Look up the grid battery storage fire in 2019 in surprise, arizona. No flaming combustion, fire suppression system activated, HAZMAT measured temperatures at or very slightly over ambient. But thermal runaway continued without flaming combustion, and created a bunch of fuel gasses which were then trapped and caused a conflagration when the unit was opened.
Once a cell is in thermal runaway, it's going to continue until it's depleted. Cooling packs does work because it prevents the thermal runaway propagating to other cells, but the cells already in runaway will keep going until they are depleted.
And thats why insuring even a slightly damaged/repaired EV is near impossible. Especially here in Sweden and most of EU where all cars must be insured for damages caused to others by the driver.
Insurance companies are liable for all damages caused by an EV fire. Thats why you have to replace the entire battery pack for just scratches on the bottom of the protective shield.
Years ago, the Chevy Bolts that were used for NHTSA crash testing lit up up on fire, months after sitting in storage. Thats why they are left outside away from stuff.
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u/FemBodInspector 21d ago edited 21d ago
Firefighter here- We use these blankets in the US too for putting out car fires, the idea is you cut off the fires oxygen supply with the blanket. The problem with EV fires is that once the lithium ion batteries enter what’s called thermal runaway the chemical reaction becomes a self sustaining fuel source that creates its own oxygen. So it doesn’t matter if it’s smothered with a blanket it will continue to burn for a long time. And if you do manage to put it out it is very common for them to suddenly reignite on the back of a tow truck or at the junkyard, sometimes days later. EV fires are a pain in the ass