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Re: Laptop battery

On Fri, Feb 17, 2006 at 01:19:32PM -0500, hendrik@topoi.pooq.com wrote:
> > 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 
> 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 conpletely.  And I've heard that the MiMH 
> batteries don't have a battery memory problem at all.

My little exercise wasn't so much about classic "memory" effect in older
battery technologies, but more about the monitoring hardware reporting
empty prematurely, since the juice is there to run another hour, but the
battery status says its empty.  Once it's seen real empty, it can better
report to the OS.

John M Flinchbaugh

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