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.
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?
Personally I’d go for an aqueduct type system
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
but that turns to gas as soon as it’s released into ambient pressures/temperatures
Which is what causes it to cool stuff.
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
Reference
Find me any proof of any lifepo4 cells having a self-oxidizing event. Spoiler alert: you can’t, because there’s no reaction that can happen with lifepo4 that will strip oxygen out of phosphate. UL listed companies sell lifepo4 batteries as non-combustible. I highly recommend looking into modern battery chemistry, becase they’re way safer than people think.
There’s plenty of proof in academic literature. FePO4 is quite stable because of the quirks in iron’s valance up to about 500C. But the combination of of lithium skews the valance effects at high temperatures to start losing oxygen at 250C.
Please review the following literature for more information:
- C. Delacourt, P. Poizot, J-.M. Tarascon, and C. Masquelier, Nat Mater., 4, 254 (2005).
- J.L Dodd, R. Yazami, and B. Fultz, Electrochem. Solid-State Let., 9, A151 (2006).
- G. Chen, .XSong, and T. J. Richardson, J. Electrochem. Soc,. 154, 4627 (2007).
How much oxygen are we talking here? I’m guessing not much, as they wouldn’t be allowed to sell lifepo4 batteries as non combustible if they had any real chance of causing a self sustaining fire. So level with me so I don’t have to trudge through a bunch of academic papers: How much oxygen do they mention?
The stoichometry comes out with 2:1 moles of lfp to diatomic oxygen which is significant
The combustibility you’re referring to is a legal definition not a scientific one
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.
Even the grown-up version of that sounds incredibly cool. Thanks for sharing!
Perhaps using a free radical scavenger in the water might inhibit further combustion of the electrolyte.
https://www.sciencedirect.com/science/article/pii/S2095495620307075
That’s remarkably close to Tesla’s estimates reported in their first responder guide.
No /s club? I had to look it up, lol to make sure…
https://www.tesla.com/sites/default/files/downloads/2017_Model_3_Emergency_Response_Guide_en.pdf
USE WATER TO FIGHT A HIGH VOLTAGE BATTERY FIRE. If the battery catches fire, is exposed to high heat, or is generating heat or gases, use large amounts of water to cool the battery. It can take approximately 3,000 gallons of water, applied directly to the battery, to fully extinguish and cool down a battery fire; always establish or request an additional water supply. If water is not immediately available, use dry chemicals, CO2, foam, or another typical fire-extinguishing agent to fight the fire until water is available
So 36,000 gallons is roughly 1200% more water than in the Model 3 emergency-fire manual, at least.
3,000 gallons of Tesla water, 12,000 gallons of normal water.
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’d rather see them contain it with sand or gravel and let it burn itself out rather than waste thousands of gallons of water trying to cool it off enough to stop it. Foam is also an option as is usually used with chemical fires.
The smoke from the fire is extremely toxic, so letting it burn out is a bad idea. Plus, it’s not wasting water, since the water isn’t removed from the environment.
I’m not sure you understand what waste means here. Of course water is never removed from the environment unless it’s sitting in storage containers. I’m going to assume (I know) that you know what I meant and are just being precocious and pedantic.
As for the smoke. Yes it is dangerous but we deal with that all the time with fertilizer plants going up in smoke, trains derailing, etc. Cover the ev with enough sand or other similar material and that will absorb some of the toxic shit, the rest will just go to the sky and hopefully not kill anything flying overhead. Those of us on the east coast literally (and yes I mean literally) just dealt with this earlier this year with the Canadian forest fires. Smoke was making it’s way as far south as the Carolinas and even this far south people with allergies, asthma, etc were feeling it.
As I said. I’d rather see them let it burn itself out. Unless they are using non-potable water that we don’t want to drink or there happens to be a major water source close enough.
They have alternative methods. These folks need to learn how to deal with these. I’m pretty sure other ev fires have had foam or sand of some sort used or you just let it burn. I’d bet this fire department would use water on a grease fire.
Id like to see that… What?! it’s for science
The interwebs has plenty of videos of what happens when water hits a grease fire (if that’s what you are talking about).
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.
So you’ve chosen a lab manual from some small classroom in some university out there.
Sure, lets get into a citation war. My choice of citation is the US Fire Administration. See here: https://www.usfa.fema.gov/blog/ig-062322.html
Listed is many EV manufacturer’s official recommendations for how to fight an EV fire. I’m choosing a large, well respected EV manufacturer. Lets choose Rivian for sake of this argument.
https://www.nfpa.org/education-and-research/emergency-response/emergency-response-guides/rivian
Page 23 of their manual states:
Oh look at that? They say to use thousands of gallons of water (2000 to 3000 gallons for the initial fire), and then work to keep the Li-ion cells below 100C for at least the next 24-hours (which is obviously easiest in what I’ve discussed elsewhere in this thread: a full submerged container). I’ve seen other fire-department manuals recommending 7-days (a full week) of submerged cells just to be sure.
In practice, fire-departments do not have the equipment for that long-term sustained cooling. So they end up baby-sitting the car for like 8+ hours and keep spraying it with a hose every few minutes, wasting tens-of-thousands of gallons of water. Its not the best solution and its a high cost both in water and fire-department’s time, but it does work when a container (or other device) is unavailable.
Step 1 only extinguish if you have specific need to.
They recommend letting in burn unless you must extinguish it actually.
Sure, you win. That was the first result that came up for me on google. If I have a class B fire extinguisher around then I’ll use that before using water.
The problem is that a fire extinguisher only works on the initial flames. If the battery pack remains overheated (as is the case in a large vehicle fire), it will spontaneously combust a few minutes later. This problem is well documented in all the fire-department manuals / discussion on EVs.
So you’re literally spreading misinformation on how to properly fight an EV Fire. I mean, not on purpose or whatever, what you’re saying is a common misconception. But IMO, its in our best interest to spread the proper firefighting tactics across our society so that everyone’s on the same page on the dangers here.
Well, I don’t have an EV and I’m not a firefighter, so EV battery fires aren’t on my radar. If I had an EV and it caught fire I’m not going to try and put it out. The biggest batteries in my life these days are less than 2kWh, so I’m going to use the class B fire extinguishers I bought after I’ve already called the fire department.
Maybe don’t comment on the subject then?
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.
