In newer vehicles from Audi, Seat, Skoda, Volkswagen, and Bentley, the status of the vehicle battery can be queried via the
battery control unit (address 61).
Here, the battery management system displays the status of the battery in blocks 19 and 20.
The values displayed in VCDS are estimates of the current state of the battery and allow for potential failures to be detected early on.
Background information on battery management:
http://opus.kobv.de/tuberlin/volltexte/2006/1383/pdf/fabis_radomir.pdf