Can you run lshal --monitor, then unplug the AC adapter and see if anything changes?
** Changed in: kde-guidance (Ubuntu) Assignee: (unassigned) => sebas Status: Unconfirmed => Needs Info -- Screen brightness not altered when AC adapter is unplugged https://launchpad.net/bugs/72120 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs