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Comment by bleepblorp | Hacker News Reader

You'll make a fortune if you can find a way to convert 40-150 KWhr of electrical energy to heat quickly enough to make a difference in an emergency situation without causing the car to combust (or explode).

You'll make a fortune because you'll have broken the laws of physics.

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A big firehouse is 184 Megawatts of cooling (assuming it is all vaporised). That will empty your battery in literally 2 seconds if you can direct it well enough... No breaking physics laws necessary.

That's not a good way to prevent them from catching on fire, though. Discharging lithium batteries that quickly is almost a guaranteed way to set them on fire.

I did a tour of an 80 MW coal power plant during my electrical engineering coursework. You're not going to fit an 184 MW heat exchanger in the garage the car gets parked in, much less the battery pack under the floor.

Also, as the article suggests, carbon monoxide is bad, and obviously you need oxygen to breathe, but firefighters have equipment that can help with that. However, when you've directed all the energy in the battery into a couple hundred pounds of water, the resulting 100C steam will instantly give 3rd degree burns to anyone in the airspace within a 10m cube around the vehicle.

Vehicles hold a shocking amount of energy to be able to transport thousands of pounds of steel for hundreds of miles. Because burning gasoline is a visceral experience, no one suggests that at arrival to an ICE car you should vaporize and exploding 20 gallons of fuel. Instead, you must prevent the fuel from burning.

It's almost like we should tax unsafer lithium tech used in sports and truck/commercial EV's more than LiFePo2, NMC and other safer but less dense chems.

Vapor expands, by a lot. Assuming that firehose delivers ~100 liters per second, you'd also create a steam bubble about 80 meters across.

That's only enough energy to vaporize about 200 kilos of water. How much coolant is already in a Tesla battery pack?

That's a lot of energy. Have you ever seen video of even a small steam explosion?

200kg of steam takes up 340,000L at 1 atmosphere of pressure: you've just turned your battery fire into a car shaped bomb.

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