The Ford Barn

JayJay · 10-03-2020, 04:49 PM

Folks, could use your help double-checking my logic.

The vehicle: 1930 pickup, full resto 1980, driven <1000 miles over the 40 years, I bought it in Feb 2020. Don't know much about the history other than the restorer was a body guy and I have not been too impressed with mechanical/electrical that I've seen so far. It seems to be pretty original, painted over.

Anyhow - I'm driving it regularly, used to seeing around +12A at road speed. Yesterday I was driving and saw that it was sitting hard on 0 amps. Got the usual dip to negative amps with stoplights, headlights, etc.

My first thought was "stuck cutout relay", knowing that the cutout needs to close to allow the generator to charge the battery. Whacked it upside the head to see if that worked, but of course it didn't.

Second thought was "fan belt tension". No indication of slippage (noise, rubber chips, etc.) but it was a bit loose, so I tightened it. No change.

Got to looking more today. What puzzles me is that output voltage of the generator, with our without the cutout in the system, is ~1.5-2V. Shouldn't I be seeing 6V or so at the output of the generator/input to the cutout? From my understanding, moving the third brush would not change output voltage, only amperage, right? (I haven't touched that yet).

I have no particular issue with rebuilding or replacing the generator, but I'd like to feel more confident that I've got a good chance of licking it.

Thanks in advance. Stay healthy.

JayJay

10-03-2020, 04:49 PM	#1
JayJay Senior Member Join Date: Jan 2020 Location: SF Bay Area Posts: 1,165	Bad generator? Folks, could use your help double-checking my logic. The vehicle: 1930 pickup, full resto 1980, driven <1000 miles over the 40 years, I bought it in Feb 2020. Don't know much about the history other than the restorer was a body guy and I have not been too impressed with mechanical/electrical that I've seen so far. It seems to be pretty original, painted over. Anyhow - I'm driving it regularly, used to seeing around +12A at road speed. Yesterday I was driving and saw that it was sitting hard on 0 amps. Got the usual dip to negative amps with stoplights, headlights, etc. My first thought was "stuck cutout relay", knowing that the cutout needs to close to allow the generator to charge the battery. Whacked it upside the head to see if that worked, but of course it didn't. Second thought was "fan belt tension". No indication of slippage (noise, rubber chips, etc.) but it was a bit loose, so I tightened it. No change. Got to looking more today. What puzzles me is that output voltage of the generator, with our without the cutout in the system, is ~1.5-2V. Shouldn't I be seeing 6V or so at the output of the generator/input to the cutout? From my understanding, moving the third brush would not change output voltage, only amperage, right? (I haven't touched that yet). I have no particular issue with rebuilding or replacing the generator, but I'd like to feel more confident that I've got a good chance of licking it. Thanks in advance. Stay healthy. JayJay