I think I would put a charger or tender on the battery and make sure it is "topped off" then take fresh readings, then drive and get updates. Just to have a solid baseline.

The IBS and voltage regulator(alternator) are suspects, assuming all is well with the battery connections and coding.

__________________
Mike

2005 e53 X5 4.8is 169k miles
2018 f90 M5
2018 Volvo XC60