If you want to contain it a bit and you don't have a metal-fire extinguisher, dump a bucket of sand or fine salt over it. Commercial metal-fire extinguishers ar

If you want to contain it a bit and you don't have a metal-fire extinguisher, dump a bucket of sand or fine salt over it. Commercial metal-fire extinguishers are nothing more than a dozen kilograms of dry, fine salt and a special low-pressure nozzle that allows depositing a "layer" of salt on the burning metal fire that melts and thus contains the fire. However it's hard to keep dry enough that it doesn't aggregate over time, reducing the effectiveness. Personally, I recommend anyone charging serious amounts of unprotected or questionably protected lithium cells in a residential structure to, first of all, not charge them while you are asleep, and to keep a 10-20 liter bucket of sand nearby. Throw it on the burning battery if you can (you should be able to hear the battery go off maybe 30 seconds before it does go off), then run for your life.