I'm using an HP Mini 2140 with Ubuntu 12.04 installed on it. Two months ago, due to the fact that my old battery lasted only for about 20-30 minutes, I bought a new battery, which reported a capacity of 50+ Wh after charging it overnight and starting up (If I recall correctly, it was 56,5 Wh) and lasted for about 6 1/2 hours at most.
During those 2 months, when checking the battery capacity with
acpi -i), I found out that after some charges, the battery capacity dropped significantly to ~48 Wh at some point. I started investigating the issue using Google and read about battery calibration. I attempted to calibrate the battery by doing a full charge, full discharge and a full recharge. The battery still reported the same capacity; however, I noticed that even after the battery had reached 0%, it would still power my netbook for a significant amount of time.
Some time later, the capacity dropped until it stabilized to 42 Wh for about a month. One week ago, I noticed that it dropped to 38 Wh and yesterday it dropped to 33 Wh. I attempted to recalibrate the battery and found out that my battery reached 0% after 4 hours and lasted 2 more hours until my netbook powered off, which means that the battery hasn't experienced any significant drop in capacity.
I also stumbled upon this article http://www.notebookreview.com/default.asp?newsID=3537, which makes me suspect that the issue has to do with ACPI.
Is there something I can do to fix or work around that issue? The only workaround I've come up with is to disable suspend/hibernate on low battery. The BIOS does not seem to have any feature to calibrate he battery and it doesn't seem possible to perform any sort of reset on the battery or ACPI.
EDIT: I'm using a non-original battery.