I just realized that UPower doesn't update the status of /org/freedesktop/UPower/devices/line_power_ACAD (no matter which kernel I use). It seems like the date in line 'updated:' is always identical to uptime.
With kernel 3.6.9 however it gets even worse: both devices are affected by this now: - /org/freedesktop/UPower/devices/line_power_ACAD and - /org/freedesktop/UPower/devices/battery_BAT1 I'll attach the output of 'upower --dump' (kernel 3.6.9-1). I had my AC adaptor disconnected for more than 10 minutes – however, upower as well as the GNOME indicator shows me I'm still connected and that my battery has 100% left. At the same time 'acpi -b' gives me 93% (which makes sense). Maybe this is a upower bug?
Device: /org/freedesktop/UPower/devices/line_power_ACAD native-path: /sys/devices/LNXSYSTM:00/device:00/PNP0A08:00/device:02/ACPI0003:00/power_supply/ACAD power supply: yes updated: Wed Dec 12 07:08:23 2012 (12018 seconds ago) has history: no has statistics: no line-power online: yes Device: /org/freedesktop/UPower/devices/battery_BAT1 native-path: /sys/devices/LNXSYSTM:00/device:00/PNP0A08:00/device:02/PNP0C0A:00/power_supply/BAT1 vendor: 13-17 model: Venturi serial: 01317 01/24/2012 power supply: yes updated: Wed Dec 12 07:08:28 2012 (12013 seconds ago) has history: yes has statistics: yes battery present: yes rechargeable: yes state: fully-charged energy: 59.94 Wh energy-empty: 0 Wh energy-full: 59.94 Wh energy-full-design: 59.94 Wh energy-rate: 0.011 W voltage: 12.391 V percentage: 100% capacity: 100% Daemon: daemon-version: 0.9.17 can-suspend: yes can-hibernate yes on-battery: no on-low-battery: no lid-is-closed: yes lid-is-present: yes is-docked: yes