Comment by daemonologist
5 hours ago
Most phones won't boot without the battery. Obvious workaround is to connect a power supply (and large cap) directly to the BMS, but in my experience most phones will shut themselves down when they think they've drawn more than the capacity of their battery, even if the voltage is still high. You can sometimes get around that by rebooting the device every couple of hours (and there might be a software/firmware fix in some cases?), but it's a lot less annoying to just accept a small risk of a house fire.
You could throw the phone in an ammo canister, if the wifi AP is close enough. When I was building hobby quadcopters, which requires several ~half-pound batteries that are a chemistry optimized for maximum power density, a lot of guys recommended steel ammo cans for battery storage.
I’m also an ammo-case-for-drone-batteries guy but they aren’t running and don’t generate heat. A phone would cook right?
Depends on how well the canister insulates it. Steel conducts heat fairly well; it'd get hot inside but I'd guess some airflow around the canister would probably keep it from getting hot enough to cook the electronics. (definitely don't take my word for it lol)
Phones are very low power, likely just a slightly warm spot on the can that radiates, conducts, and convects the heat out. You could also use one of those peltier module phone coolers, to ensure the heat gets out of the phone and into the air faster.
> but it's a lot less annoying to just accept a small risk of a house fire.
Agree! But do get one or two of those "small automatic fire extinguisher" or whatever they are, that you can attach on stuff, for electrical panels and what not, and put right next to it together with a traditional fire alarm, and you're good to go :)
No extinguisher can stop a lithium battery fire.
Putting the phone into a metal box, and the box, onto something not flammable, would help.
How many phones have you tested this with?