My experience with computers in general is that they like it cooler. Before I got the one I'm using now, my computer crashed several times a day during the summer, and not at all in the winter. (The computer store couldn't figure it out, but they had Central Air.) I'm guessing that if you leave the computer plugged in all the time, the battery life is only limited by the natural degradation (chemical reactions tend to be faster when it is warmer, though, so keep an eye on the battery temp.) When you actually work off of the battery, the battery gets warmer, so that would increase the reaction as well.