no such thing as a healthy 11 year old battery


That is s as m excellent point. The car part store only tests for high amperage and ignored voltage drop if s as MPs are high. V must have tipped low enough to screw up the electronics. I’m surprised BMW didn’t require electronic suppliers to build in the capability to bridge a short voltage drop. The cost to do that is minimal and almost inconsequential for devices which cost as much as an infotainment domain controller or head unit.

I’ll install a new battery and see if that helps. Our Ml350 has dual batteries (a smaller secondary). I wonder if the purpose is to keep V up for critical electronic subsystems…

John