Yep - leaving it in will leave it on a constant drain & charge recycle. Tbattery will not hold it's charge while you are using the mains, so it will drain slowly. After a bit, the laptop will notice and recharge it. This degrades the battery performance and eventually it will not work as well as it originally did. I have had this as my work computer is a laptop. Though, I also never bother taking the battery out :-)

Saying that, this means that you're in a bit of a Catch-22 scenario in that when you then do eventually need your battery, it is quite likely to have trickled down to nothing as you've left it on a shelf.

Battery tech is getting better, so on the newest models this may be less of an impact as it used to be.

I don't think so. Mine has a thing on it that says removal of the back cover will invalidate the guarantee. It wouldn't be possible to remove the battery without removing the cover.

Sometimes the battery acts as a 'Smoothing Capacitor' in the Power Supply Unit.

http://www.reuk.co.uk/Smoothing-Capacitors.htm

Thinking as i'm typing -

Partially it depends on the type of battery that's used -

Whilst sias74 could be correct about a 'memory effect' (to give it it's proper name), this only applies to Ni-Cad batteries...

...if it uses Li-Ion ones this doesn't happen as they are not susceptible to this effect.

However, whilst the 'memory effect' occurs when a Ni-Cad battery isn't completely drained of power before re-charging, the tiny amount that is lost by it sitting in the laptop whilst you've got it plugged into the mains will be far less significant compared to not completely draining the battery before recharging every time (which would make using the laptop impractical), & so will be of negligible importance.


Added to that, constantly taking the battery in & out risks damaging the battery compartment & the battery itself - well, anything that can be taken on & off has a more limited lifespan the more times it's done.


Otherwise, blacksmith's idea's a new one on me, but it does seem fairly reasonable...


i guess the only reason i can think of to take it out would be if the battery were getting warm whilst the laptop was in use as it would save a tiny amount of power, though almost certainly too small to be noticed on your electricity bill.

Mine is ok sheps, had my laptop 4 years now. if and when i use it, i run it on the mains. But dont aks me what batteries are in as i dont know..oops.

NO, not if its a decent laptop. The battery shouldn't discharge and recgarge as discribed by siasl74. When you plug it into the mains, it should run from the mains. At the same time, it will re-charge the battery. When the battery is full it will stop charging. It should not run off the battery while it is plugged into the mains. You should be able to look at the status through Control Panel or on the status bar