Falcon21,

hobbdebub has mostly answered your question. I have one or two points to add:

1. A rechargeable battery has a life............something like 500~ (where ~ is the symbol for the discharge/recharge cycle) so it won't last forever.

2. Most rechargeable batteries come with an initial charge (they DID test it, I hope) but this is well below its potential. You need to charge it to its fullest first time, then discharge it, then recharge it to "form" the battery, so that it will work to its full capacity.....that's what hob~ has told you.

3. By overcharging, I do not think that the sales guy was electronically inaccurate in his terminology. He should probably have said "overwork" or "stress" or something?..........we probably use different terms this side of the "Pond"

My view is that if you are going to use the device as a true portable, then you just "form" the battery and get on with it. If you are just using a laptop because of its small footprint (size) and for portability; but will be using mains power , then please disconnect the battery once "formed" and fully charged. This will considerably prolong its life. Just re-connect, and recharge every week or so.

My basic message is that if it is going to be connected to mains power most of the time, disconnect the battery.

Hope that helps,

Cheers