It Took 36,000 Gallons Of Water To Extinguish A Burning Tesla
It Took 36,000 Gallons Of Water To Extinguish A Burning Tesla
A new crash recently in Alabama, but a reminder to something that we all know. Burning Teslas are far more difficult to extinguish than any other car.
FYI Lithium and Lithium-ion are two DIFFERENT battery chemistries entirely. Lithium batteries are primary type cells, meaning not rechargeable (there are some secondary/rechargeable in work currently, but not common yet). You don't want to put water on a lithium battery due to the lithium metal. However, you typically only find lithium batteries in coin cells (think your watch/fob battery), so big fires are extremely unlikely.
Lithium-ion is a separate chemistry that is a secondary, or rechargeable, type cell. Because the lithium is bonded to a metal oxide (Co-O2, FePO4, NMCO, etc), the lithium is stable and water can be used.
In any case, it's difficult to use water for EVs because they're designed to be watertight, so you're trying to put out a self-sustaining fire/chemical reaction that's in a box in a box inside several dispersed cells.
This is not an electrical fire, as there's no sustained voltage. Once the cell fuse pops, you're only dealing with a single cell internal voltage of 4V (for lithium ion).
I've personally burned LFP cells in an inert nitrogen pressure vessel and they very much do burn. They're "better" than more reactive chemistries like NCA and NMC, but they do still burn (see story of burning teslas). That battery compartment likely has very little air in it, due to the large volume of gas vented during thermal runaway.
Let me know if you have any questions.
I’ve personally burned LFP cells in an inert nitrogen pressure vessel and they very much do burn. They’re “better” than more reactive chemistries like NCA and NMC, but they do still burn (see story of burning teslas). That battery compartment likely has very little air in it, due to the large volume of gas vented during thermal runaway.
This was the tidbit relevant to the most discussion down thread. I appreciate your knowledge! Thanks for sharing your experience.
I should also clarify when I say burn, I mean strap an electrical heater to a battery and observe the response. Heater is meant to represent an internal cell short circuit failure (which is typically cited as leading reason for thermal runaway outside of bad/defective battery design)
What is your job and would one get into that field if one were so inclined. And how much of your job involves setting things on fire for science
I don't get to set stuff on fire as much as I did in grad school, but I still get to do it occasionally (typically cost, safety, time, etc limitations). I got a degree in mechanical engineering then stayed on to do experimental fire research on lithium ion batteries. Now I help design battery packs that can withstand single cell failures without blowing up completely. Basically I keep a small fire from turning into a big fire. The main trade off is mass/volume of the battery pack, but the latest tech is getting really good in terms of performance.
In grad school, I would've tested the hell out of all my ideas. Now, my time is worth something and I have to be smarter about it. Typically model/simulate several ideas, optimize the best of those ideas, then test the best ideas based on preliminary simulation results. Iterate based on test results and so on.
Not a fan of Tesla or the lack of infrastructure the fire departments have on fighting lithium fires (might need to mandate manufacturers fund that tech, resources, and training?) To give an idea of the amount of water that is. An average residential pool 32 x 16 ft (3ft shallow/8ft deep) is 20,000 gallons. So 1.8 pools of water to put it out. I'm not sure what an average gas powered sedan takes to put out when it goes up, but I know water is also not the best choice. I think this just furthers the argument for cheap/free public transportation rather than everyone driving their defacto second living room around.
Europe's got the right idea.
Yeah, its still a ton of water to fill up, but this is far less than the 36,000 gallons used for this Tesla here. We need to start building these containers for the EVs and giving fire departments the right tools for "full submerge" strategies as EVs become more popular.
Perhaps using a free radical scavenger in the water might inhibit further combustion of the electrolyte.
https://www.sciencedirect.com/science/article/pii/S2095495620307075
Why the hell are they using water on a lithium battery fire??
Because that's how you put out a lithium battery fire. The fact that the batteries use a lithium based molecule doesn't mean it'll react violently with water.
Sodium is highly reactive with water, but table salt isn't.
Do you think firetrucks have masses of expensive chemicals stored inside of them or something? Fire equipment in the USA is water based. Fire engines have a tank of water that they keep ready + a pump for remote areas, but also a pump to hook into the water-mains if a fire is close to plumbing.
Water works to cool down Li-ion fires and will stop the fire eventually. But it takes a ton of water to do so, mostly because the water dribbles out wastefully. In Europe, they use water still but instead they have:
This prevents the water from dribbling out and actually cools down the battery pack to the point that its safe enough to tow at least. IIRC, the fires can spontaneously erupt over the next few weeks still, but at least the main fire is put out.
Which is why we don't use water on lithium fires. Fire departments need new ways to extinguish ev fires. Maybe some thick foam or a load of sand to dump over the ev.
Cooling down the reaction is the only way to stop the fires. The chemical reaction is self oxidizing so you can't smother it.
I've worked with a lot of robots/machines with large lipo and LiFePO4 batteries and as far as I'm aware your best bet is to let it burn and try to prevent the surroundings from catching fire. Using water can make it burn longer.
https://www.youtube.com/watch?v=NeaK9V69Xks
Water does work to suppress Li-ion fires. Its important that we spread this news because many people online confuse Li-element with Li+ ions. They work very differently in practice.
It just takes a LOT more water than you probably expect. But high quantities of water is effective. As Li-ion batteries become more common in our devices (and even vehicles), knowing that water is a usable solution is helpful. We obviously need to develop better tactics than dumping 36,000+ gallons per car fire however.
"NEVER extinguish LiPo batteries with water."
When in doubt, use a class B fire extinguisher.
Why are they using water to extinguish an electrical fire? That doesn't work. The fire department should know that. I'm concerned about the qualifications of the Alabama fire department.
It's not an electric fire. Lithium battery fires are a self-oxidizing runaway exothermic chemical reaction. The only way to stop it is to cool it down.
Everyone uses water to put out EV fires. Because it does work, it just takes a long time and multiple fire-engines worth of water.
Until someone comes up with a better solution, that's all we got. I'm pointing out the European solutions in this thread because they seem more feasible (using "only" thousands of gallons, rather than tens-of-thousands of gallons, of water). But water remains the best idea to stop the reaction.
Edit: someone just educated me. Lithium battery fires are self oxidizing. I was not aware of that. My bad!
How is it the best we have? Deprive the fire of oxygen and it'll go out. Halon does a fine job of sucking the air right out of the fire.
Did no one on the truck have Google ?
Or pass 9th grade science ?
Li-ion isn't Lithium. Ions are distinctly different from the raw metal. If this were raw Lithium, of course water wouldn't work. But this is Li-ion, the chemistry is rather different.
If you passed 9th grade science, you'd remember that Li-ion is Li+, suggesting a dissolved salt in the chemistry. And as you know, Na+ (Sodium+ ion) has completely different chemical reactions than Na (Sodium, aka explodes in water). Na+ in particular, dissolves in water safely. Remember?
Anyway, the Ions are very different from the raw element. As such, its widely accepted that Water is effective, but just barely so. You need lots-and-lots of water to extinguish a Li-ion fire, and the water needs to be applied for hours.
It's pretty clear from the comments that people don't really know anything about lithium batteries. OP actually knows what their talking about for the most part.
First, lithium batteries contain little to no elemental lithium. Just because the molecule has lithium in it doesn't mean it'll react violently with water. Think about table salt. Just because elemental sodium reacts violently with water doesn't mean table salt will.
Secondly, it's not an electrical fire. A lithium battery fire is an exothermic, self sustaining chemical reaction.
Thirdly, that chemical reaction is self oxidizing, so you can't just smother the fire to put it out.
The only way to stop a lithium battery fire is to either let it burn itself out (which is bad because the smoke is highly toxic), or cool it down enough so it can't self sustain. Water is very good at this.
This is the best comment in this thread. Imo a better option is not to change the cooling fluid, but to have a water connection that allows firefighters to flood the battery instead of just spraying on the vehicle
A giant bucket or water balloon?
Perhaps liquid nitrogen or even liquid co2 would be something to try to stop the reaction.
Co2 isn't liquid on earth. Maybe you're thinking of supercritical co2, but that turns to gas as soon as it's released into ambient pressures/temperatures
It's not self oxidizing. Old lithium cobalt oxide batteries were, lithium iron phosphate batteries aren't.
Phosphate will decompose into phosphate ions and oxygen given enough energy. The energy of the P--O bond is greater than Co--O but ultimately means that LFP batteries are also self-oxidizing but less so than lithium cobalt oxide
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