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Gentlemen,

I'm dealing with a charging issue and have determined that the voltage regulator is working intermittently and new one is on the way.

Now I am wondering about generator performance. After grounding the field terminal, a voltmeter at the battery shows about 6.6 volts at idle with no accessories/lights on. I get about 6.49 volts at very fast idle with accessories on.


Are those voltage numbers a concern?

Thanks,
Mark

The battery voltage at engine idle with the field grounded doesn't really mean anything, generators don't begin to have output until the generator rpm is increased. If the battery reading stays below 6.6 with the engine at atleast 1000 rpm or a very fast idle, your generator is not producing output, or it's not reaching the battery. Having electrical accessories on at the same time as the test probably doesn't effect the result, but it's not the way I was taught to do that diagnosis.

Have you pulled the brush cover and taken a look at the communtator and brushes?

Kind of uncommon for a regulator to work intermittently, usually they either work or they don't. Once in a uncommon occasion just burnishing the points will solve it.

What O_D said. Typically at a very fast idle you should be seeing approx 7 to 7.5v at the battery. Specs in SC Vol 19 #10 say it takes 6 1/2 to 7v to close the cutout relay in regulator so if generator is not working or putting out at the low end of that range that could be part of your intermittent problem. Without the cutout relay closing the generator is not connected to battery. I would suspect brushes but another possibility is generator is in need of polarizing if it or the regulator was disconnected or removed during all the work you have been doing.

Thanks guys, my understanding is increasing, perhaps painfully so. Maybe you are interested in the rest of the story.

After a 40 mile, relatively high speed drive with headlights on, and a 3 hour rest, we experienced a dead battery. Battery was fully charged before we left home. This was an AACA cruise and before I knew it, I had about 6 heads under the hood. Strange thing was that a jump would not turn the engine over. Some of the boys surmised a jammed starter or other starter/solenoid issue because power directly to the starter would not turn the engine over. I could not witness that procedure because I was in the car.

Got the car home, put a trickle charger on the battery overnight and it started right up. Battery appears to be holding a charge. In subsequent start ups, I noticed that the ammeter would sometimes show nothing (all the way to the left) and sometimes a "normal" charge. So, I concluded the VR was intermittent. That and the problems other posters have had with VR's. Jason rebuilt the starter and generator a couple of years and perhaps 1500 miles ago, so they were not initially suspect.

Given that the engine started normally several times yesterday, I am dismissing that failed jump start as operator error or a mystery of the universe.

So, I'm attempting to go back to basics here. I'll keep at it and examine the generator, and will check the wires on the ammeter. I noted that the points in the farthest inboard relay were not aligned very well...is that the cut-out relay?


Thanks

... I noticed that the ammeter would sometimes show nothing (all the way to the left)

All the way to the left isn't NOTHING, it's a very large discharge! Short circuit?

Right Owen, my statement was wrong. Intermittently, the ammeter needle would stay slightly to the discharge side during acceleration, and sometimes the needle would go well into to the charge side on acceleration. Would a sticking or malfunctioning cut-out relay cause that display in the ammeter?

Any evidence the cut out relay is sticking. Hard to say which one is the cutout because arrangement varies by mfg and number but it should be the one connected directly to the BAT terminal. At any rate, If cutoff points stuck closed that would be a large discharge thru the generator. Generator would be very hot to touch and if belt were loose enough it would even try to turn like a motor.

I just went through the same problem. My charging system has been intermittent for more than 10 years. I replaced the regulator several times, and had the generator rebuilt twice. This spring, I took the generator out once again and opened it up myself. There was no sign that anyone with any skill had been inside the generator. One of the main things I noticed that was not right was that the two brush springs did not have the same intensity, and I believe that one of the brushes was not being pressed onto the commutator like it should have... causing the intermittent problem.

I sent it to a more reputable shop, and while it was out I had them install sealed bearings. I had immediate positive results after reinstalling the generator. Made the trip to the AACA national meet in Auburn, Indiana last weekend without any intermittent problem. Came back at night, and no problems either.

Didn't we have a simular problem like this last year on this forum and it turned out to be the battery? I'm just throwing that out there to see if anybody remembers that problem.
Wes