Single-Wire Alternator Questions Again

[Sledge]

Folks:

I've got a Powermaster 100-amp single-wire alternator in my BDR. I do not have a stereo or other massive power drain, just the juice required to run the engine, fuel pump, lights, and the two aux cooling fans.

I don't understand what my voltmeter should be reading when the car is running. Sometimes it reads 15 volts or so, other times it reads less than 12. I drove my car down to San Diego (in daylight, lights off), and while cruising on the freeways (the aux cooling fans were off) I watched the voltmeter go from 15 slowly to 12-, then return slowly to 15 volts 15-20 minutes later. It did this two or three times during the trip.

When I started the car to bring it home it initially read 15 volts, but for the last 70 miles home it read 12- volts for the entire distance--no cycling, even with the fans coming on and off (traffic jam). Again, this was daylight with lights off. When I next started the car (a couple of minutes after getting home) and drove it for a couple of miles, the volt meter stayed at 12-.

Are the above indications normal for BDR installations? I'm just looking for feedback from other BDR owners with single-wire alternators as to what "normal" volt indications are or should be; just a baseline starting point. I've asked these questions before but most responses tied the variation in the voltmeter to heavy electrical loads, which weren't present in this recent trip as the lights and fans were off. So I guess I'm cross-checking against previous responses, and looking for new additional input if there is any aout there.


If it isn't normal then I've either got a gauge problem or another failed or failing alternator, or maybe a wiring problem, so I've got more troubleshooting to do. I've got 1100 miles on the car. Armond hasn't been able to help me much in ths regard, although he replaced the first alternator under warranty, and I'll be talking to Reg on Monday if I can get him. I haven't invested in an alternator output meter yet, was hoping I wasn't going to have to.

Thanks and cheers

Bill