Comment by jchw | Hacker News Reader

Comment by jchw | Hacker News Reader

I didn't read the entire paper, but what I was really curious to hear about was battery chemistry, and I didn't see much in there (unless I just missed it.) I've been bullish on LiFePO4 because of the ostensible safety benefits, but it would be interesting if anyone has taken a look at the safety risks of different battery chemistries head-to-head.

I don't necessarily think that lithium ion batteries are inherently unsafe, but even if their safety properties are in fact acceptable on a societal level, it's hard to grapple with how horrifically violent battery fires can be. There was a video going around of a battery fire where someone got trapped in an elevator with, apparently, an e-bike battery that went into thermal runaway. It's hard to overstate how utterly mangled their body was. Even as someone who grew up with access to LiveLeak and other things I shouldn't have seen, that video and the decimated (shockingly alive, but not for much longer) corpse pulled out of the elevator will be sticking with me for a long time (and reminding me to not bring potentially sketchy high-capacity batteries onto elevators, for whatever it's worth...)

How large was the elevator ? Scary but I wonder if you had time to react if you could shove the bike to the opposite side and maybe be relatively fine

I saw the video. It was a very small car, the kind you would see in a small apartment building - something like 4 feet square or 1.25m square, if even. Basically a closet. Edit: to add it wasn't the whole bike but the battery pack itself. It was in his hand.

Pretty small, but I'm not sure if it matters. If any battery starts out-gassing when you're in an elevator, you're probably as good as dead, because the hydrogen fluoride release will quickly cause tremendous damage to you or just flat out kill you; I doubt there's much you can do about it.

So I definitely think that the moral of the story is simply never, ever take a large battery onto an elevator

Maybe solid state batteries can some day give us more peace of mind.

The video shows the entire elevator being engulfed in fire, fumes and light. It was a small lift, but I'd doubt any part of any normal lift would have a safe spot.

Here's a NSFL link of what appears to be the video for those wanting to see just how engulfing it was https://streamable.com/y47pm1

For those wanting to stick to descriptions: the entire elevator (albeit a smaller one) is goes from normal to completely filled with burning toxic gasses in 2 seconds. If it were a large elevator and a phone battery you could probably escape most of the damage by being at the opposite end and exiting quickly after. With a batter that large though it's a bit of a different story.

Being trapped in an enclosed space with something like that, which supplies its own oxidizer and burns very hot, would be a nightmare. It's like wondering if your food can retreat to the safe corner of your oven or BBQ, away from the burner.

As stupid kids, my friends and I found an unused emergency road flare and played with it, outside on a sand pile, where we thought it safe. I still managed to get give myself some lung injury from inhaling a shallow breath from the invisible convection gases rising off it about 3 feet above.

Yeah lifepo4 will not combust badly. Look up will prose on YouTube he does a lot of tests

Indeed, they also can produce toxic smoke... should be in an outdoor pit. =3

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