Ok a few things:
Batteries don’t need “a few sparks” to catch fire. They will generate plenty of heat if punctured and self-ignite.
You don’t pour water on a grease fire because grease floats and it will spill out of your pot and catch the rest of your kitchen on fire. Also the water will boil and splatter oil everywhere.
Also pouring water on a battery fire is the preferred way to put it out. Many of the chemicals in the battery will release oxygen when heated, so the best way to put it out is to cool it down as much as possible by dousing it with a shitload of water. It isn’t always possible to apply enough water to the core of the fire which is why they are hard to put out. Sand won’t do anything because the fire is self-oxidizing.
Yes lithium metal reacts with water, but that’s not what makes batteries hard to put out.
I’m wondering if EVs shouldn’t have mechanism where if fire is detected the bottom part (which holds the batteries) would simply separate and fall to the ground exposing the batteries to firemen and making it easier to stop the fire.
In the majority of cases, its still going to be stuck under a mangled car that you cant move because it is on fire. A better solution might be to route multiple ‘flood tubes’ to the battery compartment and place them in easy accessible places. That way you would just need to pop pff an access panel and hook up a hose.
You don’t pour water on a grease fire because grease floats and it will spill out of your pot and catch the rest of your kitchen on fire
I expect you know as you were mainly talking about batteries (on this post about batteries) - but grease fires are not quite dangerous just because grease floats and adding water causes it to spill fire - when you introduce the water it does sink, but then it superheats to vapour, rapidly expanding and almost erupts the oil, chucking a poor man’s napalm round everything in the vicinity
It doesn’t have to even be on fire, if the oil is >100 degrees and there’s enough of it to superheat adding water will do the same thing (minus the flames) - a melted face is better than a melted face and a house fire, but neither are recommended
I worked at a lithium ion battery company for 11 years. Water won’t do it. When ruptured, a lithium ion battery goes into something called thermal runaway. You need to use CO2 fire extinguishers to cool the batteries to get the fire to stop. Otherwise, it will burn until all the energy is used up. I suppose it’s possible to use water that’s cold enough to stop the reaction, but I highly doubt it.
Water turning into steam soaks up an enormous amount of heat. I assume that thermal runaway happens somewhere above 100C, right?
CO2 extinguishers work by displacing oxygen, not by cooling.
The rapidly expanding co2 does get very cold though. It’s not any different from freezing things with compressed air cans.
I don’t hover, know which would absorb more heat per pound though. Someone who knows more math than I can do it though.
Sand won’t do anything because the fire is self-oxidizing.
From my understanding the recommendation to have a bucket of sand around when handling lithium batteries is not to put the fire out with it, but to have something to throw the battery into that’s not gonna catch fire as well, and then to carry the whole bucket somewhere where the battery can just burn out on its own. Is that wrong?
Well now I don’t know WHO to upvote. Guy before you sound smart. You sound smart too! Me dumb! Me bang rocks together!!! RAAAHHHH!!! RAHHH!!! BORED! BORED! RIP OWN HEAD OFF!!! RAAAAWWWWWW!!!
I’ve heard plenty of times to never use water on a grease fire, but never learned why or what happens if you do. Thanks for that!
It’s a lot more aggressive than what comes through in their description. It can create a giant fireball since the water boils instantly on contact and causes the burning oil to fling up into the air almost like a flame thrower.
17 second demonstration: https://www.youtube.com/watch?v=NgO_uZA5vXg
I once set oil on fire while making stovetop popcorn while drunk. This knowledge likely saved my house.
