ideas sure, but better to figure it out
What did the ammeter show when this was happening?
That will provide clues as to where to start looking.
The ammeter goes from 40 amps discharge to 40 amps charge. The meter indicates current flowing in or out of the battery. For whatever reason, its labelled 'Alternator'. However if you see the ammeter showing discharge, when the engine is running, then the alternator is not providing enough power to cover the system needs.
The ammeter should show charging after start, then go to zero.
Sometimes it may show very slight discharge with lights and heater on at slow idle.
Then at higher engine speeds it will charge back up. Once the battery is charged, the needle again should be centered.
