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
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
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.
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.
If the car is on fire already how does this work?
It looks like you would need to drag the burning vehicle into the dumpster and than fill it with water? That doesn’t seem to be a very viable option safety wise.
Different propositions. I think this particular design you hook up a metal cable + winch the car into the container, which has the risks like you point out.
In this design, a truck slams the container from the top down, and then I think like rubber-feet on the bottom try to prevent the water from leaking out. Of course there’s more leakage here, but less so than no container at all. So pros/cons for different methodologies.
The important thing is that these designs are being tested in Europe. USA seemingly has no response yet.
My guess is an electromagnetic crane. This isn’t a good option either. Just use halon fire extinguishers.
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.