[TriLUG] apm gives wierd values for old battery

Joseph Mack NA3T jmack at wm7d.net
Sun Dec 24 19:13:24 EST 2006


On Sun, 24 Dec 2006, Ed Hill wrote:

> Its been a while since I've used APM.  For ACPI, the percent typically
> reported is the "percent of the last full charge" not the "percent of
> the battery design capacity".  Initially, the two percents are about
> equal.  But, over time, most batteries slowly loose the ability to hold
> charge so the reported percentage is a fraction of an ever-decreasing
> total.

If I understand you, we both agree. The battery after 
charging will show 100% and then decrease to 0% (if you let 
it go that far) as you use it. The change with age is that 
100% represents progressively decreasing number of mAh.

I have a (laptop - new battery) pair that shows this 
behaviour, indicating that the bios (or whatever apm reads) 
in the laptop is behaving OK. I get about 3hrs out of the 
battery with apm showing 3% charge left.

With the old battery, the laptop takes about 30mins to 
get to 73% charge, when the laptop hibernates. I would 
expect if the battery had reduced capacity, that it would 
show say 10% in 30mins.

Joe

-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
generator at http://www.wm7d.net/azproj.shtml
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