how long should a laptop battery last on a single charge?

Answer 1

Depends a bunch on the maker! My IBM has pitiful stamina: about an hour and a half, grrr... On the other hand, my HP will hang in there about four hours...tolerable.

Answer 2

There are several factors which will effect battery life. Typically they last about 3 hours. But factors such as what processes you are running, are you using wireless, how old the battery is will all factor into it (i.e. watching movies, editing video will drain batteries quicker, using a wirless connection will drain battery faster then a wired connection)