OK, latest results: the voltmeter in the dash shows 13.8V if the engine is running and no electrical consumers. If I switch on headlights and empeg/amp it goes to under 12V idling and back to 13.8V when the rpms go up. With fan at full, headlights and empeg/amp on loud it shows under 12V, even at freeway rpms (3-4k). Do you think that if that behavior continues, I should have the alternator checked out or should I rather trickle charge the battery? Or both? With the engine off, the voltmeter showed just over 12V when I left the car last night.