Another item that "excites" the alternator field winding is the red battery light in the dash cluster. The red light supplies just enough of an electrical load to enpower the regulator. So, is the red battery icon illuminated while waiting for the glow light to go out? We had this issue years ago on GMC vans with a volt gauge and no red "idiot" light. A bulletin was issued saying to wire in a lamp socket and bulb to load the alternator. If these GMC's were started on a cold morning to defrost windows and not revved up, after a week, the battery was virtually dead.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.