Radio/MID cutting out

[AV8R4AA]

I have owned this X5 fir 9 hours.
I'm having an odd battery electrical system problem.

The static battery voltage is 12.6.
Running its 14.4.
I'm checking this at the engine jumpstart terminal.

When I have the AC turned on and the radio on, it's fine.
If I add something else like I turn on headlights, the radio quits.
I think I have a decent battery and alternator.
What to check?

I have 2004 X5 4.4 engine
The battery is no name and 4 years old this month.
Alternator is unknown.

[AV8R4AA]

I have narrowed this abnormally to the headlight switch/dimmer.
I can get the radio to cut off if I rotate the rheostat on the dimmer.
Sometimes I can get the radio to shut off if I select the headlights on or off.

I removed it and sprayed contact cleaner in the rheostat.
That seemed to help a very little.
Moving the light selector I didn't do anything with.