AW: Completely discharging LION batteries

Hi!

I'm using Linux 2.4.20 together with the acpi patches 
20021205-2.4.20 on a
Thinkpad T20. If I use two batteries (the builtin and a 
second in the Ultra-
Bay), the second battery first gets discharged _completely_ 
and after that the internal battery is used.

That's normal, but yes it is not the smartest idea to do.

After completely discharging the battery, the
maximum capacity to which the battery can be charged is only 
28120 mWh,
so I lost about 2000 mWh or about 8 percent of the battery capacity!!!

Yes that's correct, but a 8 percent drop is way to much. 
It's a physical property that if Lion batteries are discharged 
completely the capacity gets smaller. Hence in areas were reliability is
important (i.e. in satellites) lion batteries are never allowed to discharge
deeply. But on the other hand, from the manufacturer point of view this is 
more than welcome. The customer has the replace his batteries sooner.

So since I found that out I don't allow the Laptop to fully 
discharge the
battery anymore. So may questions are: Can I set the capacity 
at which the
Laptop switches to the builtin battery? Can you acknowledge 
my experiences?

The strategy is set by the BIOS or by the embedded controller, there is no
way to change it.

Herbert.


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