Battery status might be reported incorrectly when attaching a second battery to a laptop running Windows Vista
Consider the following scenario. You have two battery modules attached to the same computer and keep detaching and attaching one of them. You find that the battery status is randomly reported incorrectly in some programs, such as Windows Mobility Center.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB968511.