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   Scarlet :02_dance: (scarlet@bae.st)'s status on Friday, 27-Sep-2024 23:28:16 JST Scarlet :02_dance:

   in reply to
   @lunarised
   >but we know we can use batteries as an explosive
   No we can't. An explosion requires a chemical reaction so fast, that it can burn all the fuel in a fraction of a second. You simply can't get a battery to burn all of it's content instantly like that. You can get lithium-ion batteries to burn quite fast, but even the most violent reaction will still take a couple of seconds to completely consume a battery. This is why technically you never actually have a battery explosion. You can probably compare it closer to a welding blowfire torch fire, which you still don't want to happen in your pocket or hands. If something suddenly started a welding torch to go off in someone's pants, I understand why they'd feel the need to call it an explosion, but it technically isn't.
   
   >Sure an EV fire is destructive and can take WEEKs to put out
   No. An EV lithium-ion fire will burn itself out in a matter of hours at most, though less than an hour is more likely. So "weeks" clearly isn't true.
   If you somehow kept adding batteries to the fire, sure you can keep it going for weeks, if that's what you want.
   As for putting out a lithium-ion battery fire in the classical sense of the word, it's basically impossible. You can't use water, and it's too hot to cool down with something like foam or CO2 extinguishers. You might have success if you literally bury the source of the fire in an mountain of sand. But that's not exactly easy to do. This is why the current tactic to deal with EV fires is to let it burn itself out.
   
   >that energy can be utilized by a reaction quicker than a petrol cars explosion
   But still not even close to quick enough to create a proper explosion. Just one very hot fire.
   
   >which isnt including the other energy stored in a battery, which is often cited as 20-30x the amount the battery can hold for regular discharge
   I don't know where you got this idea, but it's complete BS. A lithium-ion battery is usually considered fully charged at ~4.2V, and discharged at ~3V (here you can see a bit more variability). But the energy left bellow that 3V is actually very low. I don't think you can get even 1x the amount of energy available during the normal charge-discharge cycle. Voltage isn't everything. Amperage is a lot more important here. And the amount of amps a battery can still output below 3V is mediocre.
   The majority of the energy in a battery IS the regular charge-discharge cycle. You can find charge curves for various battery chemistries around, every battery has a voltage underneath which the energy capacity it can hold drops exponentially fast. For example, for nickel rechargeables (and alkaline batteries), it's right below 1v.
   I've attached one example I found for lithium-ion, but you can search for yourself for similar graphs.
   So no, whatever battery you're thinking of isn't holding 1 ton of TNT in it. It's holding pretty much what is written on the label. And no, the energy inside an EV battery is DEFINITELY not more than the energy inside your Honda Civic fuel tank. It just has the potential to be released faster.
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