171–175 of 175 posts
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> 12 kilos - most people can barely lift that! Not that I'm disagreeing with your overall point, but this I find particularly surprising? My electric scooter weighs 14 kilograms and I carry it everywhere. That said, adding an extra 12 kilos to my backpack would be annoying, for sure.
Huh. I add 15kg of weight plates to my backpack, for fun. And I walk to work.
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There's a physical kind of easy, and there's a financial kind of easy. I've noticed they're usually at odds with each other.
It's not especially expensive. I paid around $1800 to remove and dump 30 ecology blocks (weigh around 2 tons each). If you do it yourself, a 10 ton excavator will cost around $500 to rent for the day.
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The good news is, water is cold (generally), doesn't combust (generally), and there is a LOT of it. So spraying water, while it can make it spicier for a bit, allows you to suck away enough heat fast enough that it works okayish. It's the scalable, but not ideal, solution generally. Current guidance is don't bother with anything else, just spray it until the flames stop.
I wonder if they could add a "water flooding port" to the battery packs, to allow firefighters to hook up a water hose and flood that battery compartment directly. Seems like it'd be much more targeted/effective/efficient than trying to spray the exterior.
That length of time may be zero if the reason it is on fire is due to traumatic damage to the battery pack from a crash or similar.
It’s easier and less error prone to spray it from a distance. If it isn’t on fire yet, maybe it keeps it cool enough it never starts. If it is on fire, just keep spraying until the bad flames stop.
Earlier quoted context omitted.
The good news is, water is cold (generally), doesn't combust (generally), and there is a LOT of it. So spraying water, while it can make it spicier for a bit, allows you to suck away enough heat fast enough that it works okayish. It's the scalable, but not ideal, solution generally. Current guidance is don't bother with anything else, just spray it until the flames stop.
The phase transition of water from liquid to gas requires an enormous amount of energy. It’s a very good substance for cooling very hot things.
Let's say you have a battery immersed in a tank of water (aside from the contacts), and you wanted to match the amount of water to the stored energy of the cell, such that, in the event that the stored energy is accidentally released, the last of the water boils away when the battery is empty.
Apparently it takes about 2.37 kwh to boil a gallon of water. That's a lot of energy, but if you have a car with an 80kwh battery pack, you'd need about 33 gallons of water, which is probably too heavy to be a realistic option.
(Granted this is oversimplistic because the energy that comes from a burning battery might be more than the electrical energy you could get out of it just by discharging it the normal way.)
I found a wikipedia article that lists joules per gram required to vaporize various substances:
https://en.wikipedia.org/wiki/Enthalpy_of_vaporization
Water is way up there. Iron and aluminum are even higher, but it's hard to imagine even an EV fire being enough to vaporize large amounts of those. I don't think I'd want to be breathing that either, though given the "battery fire" scenario I guess that's already a given.
Lithium battery fire cannot be 'put out'- in a normal sense. A fuel tank of petrol needs oxygen to burn, and when you spray foam on it your cut off the oxygen and the fire stops. A battery already contains energy, all the chemicals required for the reaction are already present, and once the energy release starts, sealing it from the environment does not stop the process. Ebike and drone batteries are large enough to…
> there is no 'battery safety box' that I could readilly buy Take a look at Bat-Safe LiPo boxes. They are designed to contain the heat and prevent your entire house from going up from a drone battery fire.