Putting out EV fires is a concern.
1 Like
When we were buying the Class D fire extinguishers, the one that will put out lithium was twice as much as the regular Class D, which will put out magnesium and rust and such. So – what fool used water on a lithium fire???
Water is not recommended for lithium fires, but if that’s the route you’re going to take then dunking the remains of the chassis in water isn’t a bad strategy.
2 Likes
I believe that the water is used to try to put the fire out before it gets to the lithium batteries.
If the batteries catch fire, it would make for a lot more fireworks.
For centuries, dousing a fire with a huge quantity of water has been effective with the exception of limited types of hazmat.
Fire departments cannot afford special battalions of dry ABC extinguishers should EVs become more prevalent. The cheapest thing may be dump trucks of sand…
2 Likes
Realizing that I know virtually nothing, what would catch fire on a Tesla that WASN’T the batteries? Carburetors and fuel have been the culprits in the average car fire, although faulty wiring can also be an issue.
How do they deal with commercial and industrial fires which often include A, B, C, and D class fires that don’t respond well to water?
This may in part be the fire marshall’s job. We had to get Class D extinguishers because of our metal usage. Although, if a fire got good and started, with no one around to use the extinguisher, they’d probably just dump massive quantities of water on it. At least, until it became obvious that that was A Bad Idea.
I don’t think there is enough lithium, or metalic lithium in an EV battery pack to warrant treating it as a lithium fire. What you do have is a very high charge density battery, that depends on certain geometry to keep the plates separated. My understanding of lithium ion battery fires is that something, either mechanical trauma, excessive heat, or electrical abuse damages the separation between the “plates” to where self discharge current starts to flow at a rate that causes further damage, and higher currents, and the self discharge is creating enough heat to both vaporize and ignite the battery components in the near vicinity, creating more areas to short out. A particularly nasty failure mode when it is a large cell.
1 Like
One of the articles I read said the container and water is to ensure it stayed cool for 48-72hrs becuase they can again overheat and reignite. The impression I got was the fire was out before they moved it into the container.
1 Like
63kg is the shoot from the hip answer
Maybe not enough to merit unusual fire suppression methods after all.
What does warrant unusual handling is the amount of watt hours stored, and the difficulty knowing when it is either fully discharged, or when it is in a fully stable state, with no more areas ready to cook off.
Did y’all see the Top Gear episode where Hammond crashed his Rimac 1 and it burned for 5 days?
1 Like
Grand Tour, I do believe. I haven’t seen any reference to how long it burned except in this Reddit inquiry:
where a commenter suggests it was 5 days…
I am amused by this article https://pluginmotorwerks.com/rimac-concept-one-safe-the-grand-tour-crash/
which asks if electric cars are safe drive owing to their electric power storage methodology… It seems pretty clear that driving them isn’t as problematic as crashing them. I am further confused that most of these articles focus on the danger to the driver/passengers, and many mention that carrying around all those liquid BTUs in petrol or diesel doesn’t exactly make for safe crashes, either, but the bigger deal from my perspective is the enhanced danger to everyone else from the innocent standers-by to the firefighters and other first responders…
1 Like
They were talking about it on the show… about how it kept re-igniting for a few days after it was originally put out.
1 Like
Skip to the very end of S2:E1 (1:08:20).
Once lithium batteries reach a specific internal temperature they go into a self-sustaining chemical fire that is difficult to put out. Class D smothers, but doesn’t reduce the temperature which is what’s required. Airline folks are taught to dump ice and dump ice and dump ice on a lithium battery that has caught fire as bringing the temperature down stops the fire.
1 Like
Consumer Reports has a tendency to avoid sensationalism and has an interesting piece on EV fires.
1 Like
Interesting. I’m wondering what the chemistry in the special lithium Class D is. I mean – does it contain something with an endothermic reaction, or is it just hype and guesswork?
There are different types of Class D depending on the chemical fire. Most are dry powder.
Wikipedia has a good list.
Most people are going to keep a copper powder extinguisher around for lithium fires and will opt to use lots of water to try and cool things down.
1 Like