I agree with Ditch999. I fully charge my battery with the laptop switched off, then remove the battery and only put it back in when i'm using the laptop away from home (which is seldom). 99% of tiem I use the machine plugged into mains and minus the battery.
Still get 2 hours use from the battery after 4 years; a friend with identical machine who kept battery in all the time AND ran on mains at same time is down to 15 mins.
Apparently my friend's action causes a constant "trickle charge" which is not good for the battery.
Different makes will be different, but I believe the principle is the same.
This thread is now locked and can not be replied to.