I searched everywhere here, and read the 'do not overcharge' your batteries thread. But this case seemed different.
This was a few years ago, when I knew NOTHING about flashlights or batteries. I'd bought a CHEAP little flashlight with lithium battery. I don't know what kind of battery, other than it was lithium. I never charged it, didn't do anything to it, other than keep it in the little 4" flashlight.
At about 1 a.m. I was awakened by a POP...there was fire on my bedcover and upon turning the light on, the window was broken. The battery had exploded and sent the battery to the window like a bullet, and something landed on the bedspread making the fire.
Anyone want to make a guess why this happened?? (I'd say the room temp. was about 70 degrees and humidity was about 70 also, if that has anything to do with it)