T0M722

I think it depends on a lot of things. Firstly the size of the laptop; my one from school is a 11.6" one and it doesn't give off that much heat, however my sisters 15.6" one give off loads to the point where I wouldn't want to leave it on for too long. I think that more heat = more battery used (also a performance laptop will give off more). Also, if you are using it continuously it will obviously discharge quicker. If you leave it to idle it will most likely go into low-battery mode and eventually fall asleep, IE almost turn itself off which uses almost no battery. In the end, I'd say this: I don't think leaving it on until the battery dies would cause it to overheat or damage anything. However, don't plug in the charger and let it sit on like that. Eventually something will overheat and break in one way or another.