High (?) Operating Voltage issue (up to 15.0V)

[TouringM3]

Hey Everyone –

I have two cars, a 328xi sedan and M3 Wagon.
The 328xi when operating stays a very steady 14.1(ish) volts
The M3 when operating ranges from 13 all the way up to 15.1

As a drive in the M3 increases in time I've noticed a couple of things:
• glovebox light flicker
• HVAC controls display flicker
• Audio system drops for a second every handful of minutes


This is leading me to think that the car's alternator isn't performing as it should, or the battery's state-of-charge isn't communicating to the rest of the car.

I have the car programmed for the 85AH battery (non AGM), but i didn't see a SPECIFIC option for the Lithium Ion battery in bimmerlink or bimmercode apps, so that could be a possible culprit?


Anyone smarter than I have insights on this?