Re: recharing and batteries

["John H. Kim" <jokim@tuna.mit.edu>]

On Sun, 10 Sep 1995, Robert Dewar wrote:

> note that, unlike some other laptops, the batteries in the Thinkpad are
> NOT "constantly charging", they only charge when they get down to 90%.
> It takes FAR longer for them to degrade to this level of charge than it
> does to top them up, so only a very small fraction of the time are they
> actually charging.
> 
> That's why I think the literature that suggests that constant charging may
> be harmful may not be relevant.

For what it's worth, 10 months ago, after leaving my battery plugged in
and on AC for over a month, it died.  It would hold a charge for about 10
seconds.  IBM shipped me a replacement which I was babying so it wouldn't
happen again.  Well, over a month ago I installed Linux and have been
leaving the battery in and on AC continuously since then, except for the
rundown once every 10 days or so.  Last night I took it off AC.  After
only an hour of use the light got down to blinking orange.  This is a
TP750 mono with the NiMH battery so I normally get 3-5 hours out of a
charge. I'll probably be giving IBM another call soon.  This battery has
only had about 50 complete power cycles.

You guys have peaked my interest, so I'll do a rundown sometime soon.
I'd like to not leave the battery in when on AC, but I'd also like to
have the battery in as a backup in case of a power failure.
___________________________________________________________________________
John H. Kim        "A common mistake that people make when trying to design
jokim@mit.edu       something completely foolproof is to underestimate the
jokim@tuna.mit.edu  ingenuity of complete fools." -- Douglas Adams