Comment 17 for bug 177570

Comments copied (and fixed) from my bug report LP: 181101:

The old interface is through the ACPI 'battery' module, and shows up as product "Battery Bay". The new interface is through the 'power_supply' module, and shows up as product 'Li-ion'.

The old battery interface disappears upon removal; the new interface indicates 0% and 'missing' instead.

The new interface seems not to emit 'change' events to HAL (as seen in lshal --monitor), so the value is not updated except on state changes.

In addition, this duplication of battery seems to halve gnome-power-manager's indicated wattage, but the ACPI power usage value given by powertop seems unaffected.

Thankfully, this didn't see, to affect gnome-power-manager's battery-life estimates, but I would imagine having these duplicate batteries, one of which never changes, can screw up any existing battery profiles.
Ideally, once the lack of events is fixed there should be a way to detect duplicates, perhaps by having the power_supply sysfs class keep a link to the /proc battery object.