Quoted:
I've read that batteries end up lasting less than they could because people keep them in their machines when they are on AC power...on AC, the battery should be taken out if you are able to.
I always left mine attached to the laptop as I thought the manual stated to leave it on the laptop when plugged in. I'm going to have to check the manual again as I think you are correct. I just read that if you aren't using the battery power for extended periods that the battery should be removed and stored not connected to the laptop.
My laptop operates fine plugged in with battery disconnected so I think I should take the battery off if not needed.
I have digital camcorder batteries that are Li Ion and they are 10 years old and work fine but I store them not connected to the mini camcorder.
Li Ion batteries are not supposed to have a memory but I read you should charge them before fully discharged.