Stephen wrote:
> On Tue, 02 Dec 2008 14:22:56 +0000, Invisible <voi### [at] devnull> wrote:
> 
>> All different versions of Acer TravelMate. None of them are young any 
>> more. (Maybe 2, 3 years old?) A few of them will run on battery power 
>> for, like, 20 minutes. But none are very reliable. Apparently they were 
>> when new.
> 
> Rechargeable batteries are funny things before Li-ion batteries, the best thing
> you could do for them was is to "work" them. That is charge and completely
> discharge them regularly. With Li-ion batteries that does not work and in fact
> it is counter productive. Li-ion batteries can be kept on charge all the time, I
> believe.
> You might be able to put some new life into your old laptop batteries by
> discharging them completely then charging then again a couple of times but if
> your laptop shuts off immediately on switching the power off then I fear that
> they are goosed.


IIRC, Li-ion batteries do have a problem with building up a *resistance* 
barrier inside.  While researching batteries several years ago I ran 
across some information, but I don't remember too much now.

If you follow a particular discharge pattern they will build up an 
actual 'film' internally on an electrode.  This would increase the 
internal resistance of the battery.  A lot of electronics detect this as 
a dead battery and shut off accordingly.  The problem is that the 
battery still does have a good charge, just a higher internal 
resistance.  If you hook it up so that a current continues to be drawn 
then the 'film' is burned off and the internal resistance decreases to 
normal.

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