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.
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.
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!