macbook battery question

[Cusp]

It seems like my mac book's battery life is horrible. I am getting a new battery and was wondering..

Does it use the battery of a mac book if it is plugged it to the wall? Also does it hurt the battery to keep your lap top plugged in?

Sorry if these seem stupid, I just always use torrents which require me to leave my macbook on for extended periods of time and I don't want a dead battery or to overcharge it and mess up the new one.

[Telomar]

It shouldn't use the battery if it is plugged into the wall as the adaptor supplies enough power to power the computer and still charge the battery at a slightly reduced rate. I have noticed from personal experience with a MBP there is a lot more heat produced if a fully charged battery is plugged in than if you take it out so it clearly does do something.

Generally it shouldn't hurt as Li batteries are designed to stop charging once they hit a certain charge meaning overcharge is no longer an issue but many things that are designed to do something do it less than optimally so if you are going to run the computer consistently off AC then you are better off removing the battery. It won't hurt the battery to be taken out just keep in mind that if you bump that cord it'll now turn itself off is all.

[Londor]

if you are going to run the computer consistently off AC then you are better off removing the battery.
No, you are not. (http://docs.info.apple.com/article.html?artnum=305336)