Looking at your
dmesg output file it appears that on boot the kernel does not recognise your battery and lists the following error message:
ACPI: Deprecated procfs I/F for AC is loaded, please retry with CONFIG_ACPI_PROCFS_POWER cleared
There is a bug report here that describes the issue you are having.
Not knowing what version of Ubuntu you are currently running or your hardware I would recommend installing a later version of Ubuntu where the kernel is a later version and checking to see if it resolves your issue, otherwise you can follow this LONG Ubuntu Forums thread to try and solve the issue yourself.