Re: Laptop battery

[Mike McCarty <mike.mccarty@sbcglobal.net>]

hendrik@topoi.pooq.com wrote:
> On Fri, Feb 17, 2006 at 01:05:21PM -0500, John M Flinchbaugh wrote:
>
> > On Fri, Feb 17, 2006 at 05:51:59PM +0000, john gennard wrote:
> >
> > > 	I've just recharged the battery which took just
> > > over 23 minutes to reach 'fully charged'. Then switching
> > > to it, in one minute I got 'Running off battery 11 mins
> > > left' quickly followed by 'running out 0 mins left'.
> > >
> > > 	Can anyone offer any suggestions (solice is perhaps
> > > too much to hope for). I've never had anything to do with
> > > Laptops before, so I'm in the dark.
> >
> > When my R40's battery life slowly dropped from 4-5 hours to 1 hour, I
> > decided to recalibrate it by running it down completely, so it could
> > have a better idea how long it really could run.
> >
> > Once the battery meter warned me that I had 0 minutes left, I rebooted
> > it to the LILO prompt, stopped it there and let it drain the battery
> > until it just died and couldn't be turned back on.  I think it ran for
> > nearly another hour after initially reporting empty, so obviously it
> > was a bit out of calibration.
> >
> > After a recharge, the battery meter more accurately reported that I 
> > had 2 hours left.  It was still degraded from original performance, but
> > I at least regained a little extra use before having to replace this
> > aging battery.
>
>
> Yeah.  I've heard elsewhere that some kinds of batteries (those with 
> "battery memory", like NiCads) can be rejuvenated by completely draining 

NiCd cells do not have "memory". I'd be quite surprised to hear that
he has NiCd cells in there, anyway. NiMH technology has displaced
NiCd completely for laptops, AFAICT.

> them.  Apparently they remember the point to which they have been 
> discharged last and start to act empty when they get back to that point.
> Other kinds of batteries (like lead-acid car batteries can be damaged 
> severely by discharging them completely.  And I've heard that the MiMH
> batteries don't have a battery memory problem at all.

Pb acid cells can indeed be seriously damaged by discharging them, but
they can also be repaired. It takes a lot of time, but such a cell
can be unsulphated. It takes special equipment.

Mike
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