| ▲ | OptionOfT 4 days ago |
| Crazy thing about these bags is that they're just containment. Once the thermal runaway has started, it's very hard to start as it brings its own oxygen, heat and fuel. Hence why many places bring a container filled with water to extinguish an EV fire, and then probably send it to a wet shredder to make sure it doesn't re-ignite. |
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| ▲ | Spooky23 4 days ago | parent | next [-] |
| My company distributed buckets filled with cat litter for containment to every branch office. We cut the rate of fire (already low) in half by containing compromised batteries. It’s something like 0.02%-0.03% which is significant given the massive scope. Something like 200k devices and about 3% with battery issues of all types. When you think about the number of flights, passengers with lithium batters and challenges of the airplane environment, it’s a hard problem. We’re lucky the engineering around these devices are as good as it is. |
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| ▲ | somat 4 days ago | parent | next [-] | | Kitty litter is not a bad choice for a class D metal fire but make sure you have the correct type. You want the stuff made out of bentonite clay, not the stuff made out of grain byproducts. https://practical.engineering/blog/2025/4/15/when-kitty-litt... | | |
| ▲ | Spooky23 4 days ago | parent | next [-] | | Sorry i should have been more precise. It's some sort of enterprise kitty litter, which is probably the material you reference and costs about 5x kitty litter. ;) | |
| ▲ | jasomill 3 days ago | parent | prev [-] | | $500 million in clean-up costs resulting from using the wrong kitty litter. Amazing. Sounds like the cleanup costs were largely related to the fact that the reaction caused an airtight drum to explode and spew radioactive waste throughout the facility, though, which presumably wouldn't apply to the "metal fire on an aircraft" scenario. I'm curious what would actually happen, worst case. Assuming the metal fire couldn't be extinguished, could it at least be contained to melt a small enough hole in the aircraft to safely land? | | |
| ▲ | somat 3 days ago | parent [-] | | The scary thing about a class D fire is that it is self oxidizing. They are very hard/impossible to put out. Usually the best you can do is isolate it from anything else that can burn and let it burn itself out, if you have the space and equipment and correct environment you can try and break it up, but that is a lot of ifs. Water can be problematic because there is a good chance it will just scatter a bunch flaming goo everywhere not put anything out. Usually the best thing to do is to stick it in a bucket of sand. Second best is to dump sand on it. Clay type kitty litter would be a good substitute for sand, it won't catch on fire, lighter than sand, it will absorb any molten residue from the fire. My guess on the plane scenario, there are enough secondary effects (smoke, insulation/trim/carpet/seats catching on fire) that would bring down the plane. but I don't think a personal battery has enough fuel to burn thru. I think the isolation bags are probably just aluminum(perhaps steel) foil. enough layers to let the infernal thing burn out without catching anything else on fire. You probably still get a lot of nasty smoke. |
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| ▲ | ozim 4 days ago | parent | prev | next [-] | | I am pretty much sacred by amount of stuff I have at home that does have lithium batteries. I try not to keep any in drawers but possibly in one open place and having fire blanket close to that stand. Fire blanket would not help much for thermal runaway but I guess it would be better than nothing for containment or at least getting that one away from all the other batteries so they don’t chain react. | |
| ▲ | ghighi7878 4 days ago | parent | prev | next [-] | | What does your company do that they need this? | | |
| ▲ | Spooky23 3 days ago | parent [-] | | Just a very real safety culture. We had an incident where a laptop with a swollen battery fell and lit up in a public way. It attracted attention and some research was done - they realized it happened a dozen times a year. Hazardous disposal options vary by location. So the question became… what should be done with these compromised batteries before they get disposed of? It’s a simple thing that costs nothing. It’s like a fire extinguisher to me - I’ve never experienced a fire at work, yet we have extinguishers and exit signage everywhere. That said, the rate of burning batteries is very low. (Like 0.001%) Unless you have a ton of people and different use profiles, you’ll never see this happen. |
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| ▲ | 3eb7988a1663 4 days ago | parent | prev [-] | | Is there anything special about cat litter? Or just cheap and abundant? | | |
| ▲ | AlotOfReading 4 days ago | parent [-] | | The common clumping litters are usually some form of clay, dried to remove moisture. It's about as nonflammable as things come and lighter than undried clay. |
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| ▲ | avemg 4 days ago | parent | prev [-] |
| I am going to ask a question that I’m a little scared to ask because I suspect it’s really dumb, but here goes: is it at all feasible or practical to have a way to jettison a runaway battery from the aircraft? I guess most of the time the problems happen because nobody knows there’s a problem before it’s gotten too out of control for that. |
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| ▲ | appreciatorBus 4 days ago | parent | next [-] | | You’d have to devise some sort of fire proof mini airlock, large enough for a laptop or whatever the largest device you expect to deal with. This would be pretty expensive and not very practical, but even if it was, then you’d have to deal with the ethical and legal issues of where it lands and whether or not it might cause a fire there too, to say nothing of injuring someone or damaging property. | | |
| ▲ | dingaling 4 days ago | parent | next [-] | | > You’d have to devise some sort of fire proof mini airlock Maritime patrol aircraft like the P-8 already have such a system, for releasing sonobuoys and float-flares while at altitude. So it's not a technical issue, more one of regulation and maintenance. | | |
| ▲ | appreciatorBus 3 days ago | parent [-] | | Sure, I wasn’t trying to imply that it couldn’t be done, only that it would be expensive and impractical for civilian aviation, especially when there are good alternatives. |
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| ▲ | joecool1029 4 days ago | parent | prev [-] | | > then you’d have to deal with the ethical and legal issues of where it lands Meh, it's a risk reduction thing. Aircraft sometimes dump fuel too in emergencies: https://en.wikipedia.org/wiki/Fuel_dumping Earth is covered with a lot of water too, if you could eject it... risk is approaching zero on dumping a flaming battery over ocean. | | |
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| ▲ | 4 days ago | parent | prev | next [-] | | [deleted] | |
| ▲ | soopypoos 4 days ago | parent | prev [-] | | it'd get caught by a bird |
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