Remove battery from laptop when on A/C power or not ???
 

Until now I have always left my battery in my laptop (IBM T40) when using it regardless of whether I charge or have the battery at 100% when on "real power".

Does it harm the battery ? I run it down to under 3% at least every 14 days. But most of the time I am on A/C power. Should I take the battery out ? :confused:

I would say that the battery performance has detiriorated by about 10% in 6 months use. Is this acceptable ?

Thanks for your input!!! :)

I think that highly depends on the type of battery. On NiCd or NiMH you should regularly de-charge it fully before charging it again fully (I would say at least once every 14 days). For LiION this shouldn't be so important but surely it wouldn't hurt to do it once every quarter.

I would agree with what ralfkrippner said.

You can leave the battery in while running it on A/C power...it doesn't hurt it all that much. I leave my battery in all the time on my T30 but I run it down once a month or so and then charge it overnight with the laptop off. In 10 months my battery life has degraded less than 10%.

IIRC, most laptop batteries will degrade by 30% after a year of constant use. But my experience with IBM laptops over the last 4 years is that the battery performance severely degrades after about 15-18 months (ie. when running on battery power, the charge will drop to about 60% as normal and then drop from 60% to 5% in less than 5 minutes). By then its time to change your laptop anyway :)

Thanks a lot for your answers. I will keep the battery in when using it all the time, because it is just more convenient.

It is a LiIon battery!!! 71WH max. capacity at the beginning, something like 64 still available if charged 100%!

Technically on the IBM's AC doesn't charge
 

At all until the battery reaches below 90%. So, if you leave it plugged it, supposedly it has stopped charging the battery. This is on the Li-on batteries and not NiMH of which I don't even think they have anymore.

Current technique is NOT to completly discharge a Li-on battery unless you are having recharge problems with it. Run it a bit, and tap it off, run it again and tap it off.

Keeping the number of COMPLETE CYCLES low is the key.

more info can be found at a GREAT website forum called thingpads.com

Some good information here... ^

As a follow up... what about AC power supplied in aircraft? And special handling or considerations for this 'special' kind of power and its usage?

Just checked my laptops 2 NiMH and 1 LiIon

Thanks for the tips

No need to discharge battery
 

Please Google "battery memory effect myth" to understand why - this is one of the most persistent urban legends around.

While it is harmless with NiCd and NiMh batteries, you will damage Li-ion batteries by doing so. Li ion batteries have a half-life that is measured by number of discharge cycles. E.g. after 500 discharges, the battery will hold half its initial charge. Purposely discharging and recharging will only shorten its life.

According to this article on Li-Ion batteries which I found thanks to CPRich's suggestion above, I seem to be doing it all wrong.

If you run for long periods on AC and you have good power you might consider pulling the battery. The heat (which can be high in a laptop case) is not so good for batter life, this contributed a lot to earily battery death in the 600 series thinkpads. I have a couple of T23's and I know they put the battery in the opposite corner from the CPU. I don't know how the t40 is layed out you might check and see if you battery is near the hot portion of the keyboard or not.