[Qsilver7]

Diving into the TIS…I’m inclined to believe that if your auxiliary battery DOES NOT have an IBS (intelligent battery sensor) connected to it…then it probably doesn’t need to be registered since it is monitored, charged, and under the control of the PCU.

Granted, some BMW models have a Lithium battery and some have an AGM battery that is located in the engine bay or other/various locations.. And if it has an IBS attached to it, when hooked up to diagnostic software, can be seen and possibly require registration if replaced.

But again, if the AGM aux battery is connected to the PCU, then it is maintained by the module and doesn’t communicate directly with the DME or the IBS, BST, and main 12 volt battery.