Why does laptop battery show < 100% charge

[Matthew Saltzman]

On Wed, 2009-09-16 at 21:32 -0500, Robert Nichols wrote: 
> Paolo Galtieri wrote:
> > This is something that has been driving me crazy over the last several 
> > weeks.  I have my laptop plugged into AC power and has been plugged into 
> > AC power for several days now, but the battery applet shows 97.3% 
> > charge.  It has been showing < 100% for several days and never reaches 
> > 100%.  The battery is less than 3 months old.  I'm running F11 with all 
> > the latest updates.
> 
> On some laptops the charger does not get started if the battery charge
> is greater than some percentage (perhaps 95%).  Saves pointless wear
> on the battery for very little gain.  My Lenovo laptop claims to work
> that way, though I've seen it go into the "charging" state when the
> battery was already near full charge.

The Lenovo power monitor on the XP side of my dual-boot laptop
recommends not starting the charge cycle until the charge drops to 80%.
I've been considering filing an RFE for the GNOME power manager applet
to make that a user-settable parameter.

> 
-- 
                Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs