this post was submitted on 27 Dec 2023
104 points (81.7% liked)
RealTesla
487 readers
1 users here now
- Posts must be about Tesla, EV, or AV
- Meta Posts must be pre-approved.
- Shitposts are limited
- No Elon Worship
- All Links must include the original title of the Content
- Sites behind Paywalls must have text included.
- Don't be an asshole
- No Image Posts
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
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.
If you’re putting people at risk to sling it up you’re better off just letting it burn. It’s gonna be write off no matter what.
Not gonna be a thing in the USA since it’s dangerous to the people who would be using it. Instead of standing at a distance and using water/foam/sand or just letting it burn.
So there's basically two phases of an EV Fire.
The initial fire, a blazing hot heat that's dangerous -- You just hit it with water from a distance. You're correct on the analysis here.
The "reignitions". Li-ion batteries, once damaged, will reignite spontaneously for hours after the initial fire. So the fire "has been put out", but we all know that its only for a few minutes. There's enough time to winch the car into these containers and fill it up with water in practice.
Its #2 that you're probably missing. Water / Foam / etc. etc. is only good at stopping phase 1 of the fire. But the next 8+ hours, you need someone to babysit the fire with a hose and keep dribbling water on it before the fire is permanently put out. Or... you know... do like a European and use a container and fill it with water, so it can babysit itself.
Sand and some types of foam prevent #2.
The person would be at risk while rigging it up, you would have to stop spraying while getting it into the box, giving it time to reignite while the person is right beside it.
This is like those fire suppression grenades, great concept, but fails in theory since they are massive safety concerns to go with them.
And it can’t babysit itself, the FD would still be onsite while the vehicle sits in the tub, just let it burn off at that point and than it’s dealt with in a couple hours.
I don’t see Europe actively using these from any research I’ve done, just a few concepts and nothing more. Since it’s a safety concern to be able to use these.
Do you have a demo of this working? A .pdf report on the amount of sand and/or foam needed to achieve this?
European fire-departments are moving towards this full-submerge tactic because it works. Its one of the big developments in firefighting technique over the last 5ish years.
When we're dealing with 1000lbs / half-ton battery packs, the sizes needed to actually effect these fires grows dramatically. I don't think that fire-departments will be in the business of carrying dumpsters full of sand to try to extinguish these fires... but I dunno, if you got some numbers on the quantity of sand needed to achieve the suppression of the fire we can compare notes.
Yes plenty of places in the states have sand as their official policy. No real difference than your water container than for the sand container, but you can also just cover it without the container as well, this is the preferred method for personal safety, just would need more.
Same is also easier to remediate than the water as well, some places use wet sand. Best of both worlds, but still need to remediate the water.
How does sand stop the internal exothermic reaction, though? I could see wet sand maybe, but just straight sand? It's not a normal fire and is self-sustaining.
Wouldn't the transport and storage of the sand be prohibitive?
Why would it?
Weighs less and is easier to store and transport than water. Also what about places that freeze? Gonna have an ice cube with a car in it after.
Not every place is with it easy access of fire hydrants, what about the middle of a highway? Both water and sand would essentially be equally cumbersome to get there.
Just because some places freeze does not mean that all of the water will turn into an ice cube. Water freezes from the top, which then acts as an insulator for the liquid below. This is how ice fishing is possible. Are you just throwing objections at the wall to see what sticks?
A better objection with regard to freezing would be the fact that leaking water all over a highway presents a road hazard to other drivers. In which case, yes sand might be the better option. That's why we have different methods for fighting them.
Water freezes from all sides… who told you that?
Rivers freeze from the top since the ground heats the bottom and sides….
How long do you seriously think it takes thousands of gallons of water to freeze? Especially with a heat source they are trying to extinguish? Can you seriously not accept that there are professionals who know a lot more about this than you?
That entirely on the temperature outside and cannot be answered, you should know this lmfao….
And you’re supposed to leave it submerged for 7-14 days. How long do you think water will stay warm before freezing…..?
I suspect it'll stay quite toasty, actually, considering it's supposed to be extinguishing a self-sustaining exothermic reaction.
It will provide marginal heat for the first little while, if it’s heating up the water that much, than you need more since it’s not enough…
And says the one that thinks water freezes top down, I don’t think we will be listening to your opinion here, thanks. You can’t even understand basic physics and you want to argue the finer points, this is a new one lmfao.
If the water freezes, that means it puts the fire out. You realize that right?
But maybe I'm the one who just doesn't understand physics.
Of course, now you need to melt the water, without boiling it since the water is contaminated, too able to pump it away for remediation. It’s a logistical nightmare.
But you realize that just because the water is frozen doesn’t mean the exothermic reaction won’t happen…. Yeah?
Edit for your edit, yeah you clearly don’t if you seriously think water freezes top down that’s not a body of water…… and ice would stop a self igniting/oxidizing exothermic reaction….
All I hear you saying is your admission that this method works to put the fire out.
Where did I say it wouldn’t? Please point it out for the rest of the class yeah?
Cool, then all your other objections are just quibbling about the details.
Buddy seems to think this is a catch all solution instead of for incredibly specific situations.
So yeah… what else would it be about except for the details….?
You also came at me arguing details, although misguided and wrong… the irony lmfao.
We are not amused huh?
Besides being the queen of England, what else do you do for a living?
It was quite funny to hear someone think water freezes top down and use a totally unrelated situational example to try and justify it.
What is your job Mr. Know-it-all?
Every fire puts a firefighter at risk. That's not a valid argument. This system does not require a person to stand right next to the fire. That's why the box is deployed by a mechanical arm.
My guess is an electromagnetic crane. This isn't a good option either. Just use halon fire extinguishers.
That's not helpful.
A Li-ion fire is a runaway exothermic reaction. You need to cool the battery pack below the runaway thermal temperature. Using water to cool the battery-pack and keeping it cool for hours is the best known solution, for now.
If you "only" use a fire extinguisher, you choke out the fire's reaction, and then 5 minutes later the exothermic reaction just continues (the battery is still hot and self-reacting at this point). The reason why water works is that it finally and sustainably cools the battery below the runaway temperature, and keeps the damaged battery pack below that critical temperature.
You can't choke the reaction since it's self oxidizing. Cooling down the reaction is the only way to stop it.
I appreciate the note about the reaction here. Chemistry was my weakest subject back in school. So I'm sure I'm getting lots of details wrong, lol.
But I've also watched what fire-departments are doing and read up on whitepapers / discussions on fire-department tactics. So while my chemical knowledge is probably terrible, I at least know what the fire-departments know and discuss.
Yeah, I've been vaping for like 12 years now (including building my own devices) and have done a ton of research into battery safety and such, so I always try to correct misinformation on posts about battery fires.
I'm sorry you keep getting downvoted because people don't know what they're talking about.
Halon extinguishers won't work. Lithium battery fires are self oxidizing.
Oh, I didn't know that. Thanks for the information.