[lillecarl]

How much distance does one pack realistically need to not cascade? Honestly I can't imagine any more than half a meter since air is an extremely good insulator. Just make sure the fire can't crawl across though cable insulation?

I've personally set RC lipo on fire with the wood-nail-hammer technique and while the fire out of the pack is intense I can't imagine it igniting another pack.

[crote]

Don't forget about radiant heat! There's a pretty much perfect insulator between the sun and Earth conduction-wise, yet it is still pretty cozy up here.

[lillecarl]

That's fair, I don't know how to calculate this but my naive assumption is a burning pack won't radiate enough to combust something 1 meter away if there's circulating air around.

[hinkley]

Precautionary principle. There’s not good ways to extinguish these fires once they start. So you kinda have to let them go. Maybe you could use some sort of deluge system or aggressive liquid cooling on the surrounding cells however. Overbuilding the delivery system but then running the pumps at their most efficient cfm except when the smoke alarms go off.

[lillecarl]

Do we use the precautionary principle when we run nuclear, build dams and burn coal as well or is this an extra thing because it's a potentially good way to reuse EV batteries? I don't think we should build these hand-me-down EV batteries near population centers, but my understanding is that the worst case scenario would be the plant burning down and releasing bad things (hello coal & natgas) into the atmosphere?

If we could develop some basic standards for packs (which voltage steps per row and some kind of connector interface standard like for charging) I think we have a really good way to maximize the lifetime and use of EV batteries to help the environment.

I paraphrase Bill Gates: There's no one energy source which will save us, many will complement eachother.

[OneDeuxTriSeiGo]

> precautionary principle when we run nuclear, build dams

Yes. Dams in particular. You calculate for various failure modes and you design around mitigating the disaster if failure should occur. That's why dams are designed with emergency spillways. If there is a bunch of rain, gate failures, etc and you suddenly have more water than you know what to do with, you have the emergency spillway as a last resort. They exist to route water in high volume out of the resevoir, often in a sacrificial manner in an attempt to prevent the dam from failing. And if a dam would fail, it's preferably that it do so at the emergency spillway than elsewhere. So there is a certain amount of "in certain conditions failure can/will happen so this is how we design the system to fail as gracefully/least destructively as possible".

Nuclear has this as well. The plans for this are called "Severe Accident Mitigation Guidelines" or SAMGs with the general practice being called SAM (same abbreviation, just drop the G). Each nuclear site has them and they are generally framed as "this shouldn't go wrong but if it does". You can try to avoid those failure modes but they can always still potentially occur and the most you can do is just try to keep the damage from spreading to the best of your ability.

[tyrshand]

"Do we use the precautionary principle when we run nuclear, build dams and burn coal as well" ayfkm?

[lillecarl]

Dams bust, nuclear blows up. It's rare but it happens. Their worst case scenarios are worse than a park of batteries burning down on a gravel/concrete park?

Your interpretation seems to be "we don't use caution when building them" which is not what I meant at all, we do but the risk is non-zero.

[eru]

> There’s not good ways to extinguish these fires once they start.

If one battery pack catches fire, you can start moving the others away from it.

If you normally keep 0.5m between them, you have plenty of buffer space to eat into.

Basically it would start as . . . X . . . with X being the pack on fire "." being a battery pack not on fire, and " " being the half metre between them. Then you move them to get:

... X ...

Where the dots now have perhaps only 30cm between them, but the space to the X is increased.

[lazide]

Eh, the math is probably pretty different with massive quantities of packs in racks.

I’m imaging every firefighter I’ve ever known suddenly having the hair stand up on the back of their necks.