Comment 37 for bug 213128

here is a good fix to put in /etc/acpi/battery.sh ( I had the same problem and fixed it by adding this to the top)

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AC_state=/proc/acpi/ac_adapter/AC/state

if grep -q "on-line" ${AC_state} ; then

    hal-set-property --udi `hal-find-by-capability --capability ac_adapter` --key ac_adapter.present --bool true

else

    hal-set-property --udi `hal-find-by-capability --capability ac_adapter` --key ac_adapter.present --bool false

fi
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