Comment 9 for bug 379599

I can confirm I'm still seeing this on a fresh install of Natty. I've got the ThinkPad x220 and the additional "slice" battery. At the moment the primary battery is fully charged and the secondary is discharging.

cat /proc/acpi/battery/BAT0/state:

present: yes
capacity state: ok
charging state: charged
present rate: 0 mA
remaining capacity: 6618 mAh
present voltage: 12852 mV

cat /proc/acpi/battery/BAT1/state:

present: yes
capacity state: ok
charging state: discharging
present rate: 953 mA
remaining capacity: 4722 mAh
present voltage: 11823 mV

So from acpi's perspective both are detected correctly. Opening up the "Power Statistics" also shows them detected correctly. But the Power Management panel widget shows two batteries, both with the same time remaining. This always stays in sync as if it's only pulling data from one battery, and since it's dropping it must be the secondary.

When the secondary battery gets down into the critical range, Power Management will erroneously see that condition on both batteries and shut the laptop down. Which is annoying enough, but there's also no option to "do nothing" when battery power is critically low. I'm forced to choose between suspend, hibernate or shut down. So if I don't happen to be watching the laptop when the secondary battery is about to run out I might as well not have it at all - any processes I have running get interrupted.