On Mon, 2008-04-28 at 19:42 -0400, Sean Breheny wrote:
> Hi all,
> 
> I've had three laptops in my life with Li Ion batteries in them. In
> all three cases (actually involving four batteries since I got a
> replacement for one), the battery capacity declined rapidly over time.
> The laptops were two Dells and a Toshiba. On one of them (which I have
> now), a Dell Inspiron 6000, the battery is perhaps 1 year old. When I
> unplug the AC adaptor, the system immediately starts giving battery
> warnings and after about 5 minutes shuts down suddenly, without even
> going into hibernation.

That battery is toast.

For anyone interested, if you boot into Ubuntu Linux (just download the
CD, it'll live boot straight to the desktop, it won't touch your hard
drive). Click on the battery icon and select your battery. It will
report the design capacity of your battery, and it's actual current
capacity. In my case I have two batteries, one is at 70% design
capacity, the other is at 53%. They are about 3 years old.

> I'm wondering if this is just the way things are (inherent in Li Ion
> technology? poor charger design?) or if I am doing something wrong.
> 90+ % of the time I leave my laptop plugged in. I have the occasional
> need to carry it away from AC power for perhaps a half hour.

There is your problem.

> I've heard rumors that it is not good to leave a laptop plugged in all
> the time unless you first remove the battery. Is this true? If so, it
> seems strange - that would seem to be a poor charger design if it
> cannot prevent overcharge.

You are forgetting one thing: heat. The #1 enemy of LiIon batteries is
heat. Any elevated temperatures will degrade the life of the battery. If
it's always plugged in it's likely your laptop isn't caring to much
about power usage and just clocks everything at top speed, for top
performance. Obviously all those watts going in have to go somewhere,
and mostly it's heat. Your batteries haven't been overcharged, but they
have been cooking.

In my case, the two batteries I have have been used pretty much
identically, and are the exact same age. The one that's only at 53%
capacity is situated right beside the CPU and GPU heat pipe, and close
to the lap. The one with 70% capacity sits in the drive bay, quite far
away from any heat source. Only a sample of one I know, but to me
telling at least a little bit.

TTYL
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