Charging system help

[Chiro]

I have a 12 volt generator on my system 235 I6. The system is not charging. Brought the gennie and voltage regulator to the local rebuilder. A quality shop. They do all the local fire department stuff so you know they are top notch. Generator checks out good. voltage regulator was bad so I installed the new one they provided. They matched the gennie and VR and did the required "flash". It is a NEW wiring harness that is in good shape.

Ammeter needle NEVER moves to the positives side. Moves to negative side when I turn on the lights. The voltmeter I installed never shows charging. It only reads whatever voltage the battery shows when engine is off. Same voltage when running. Never goes above 12.5 volts. Never gets to 13.5 volts which I believe is what is needed.

I need a step by step procedure for diagnosing this issue. How to check the VR and the gennie while they are installed in the car.

Previously car charged correctly. It's making me batty trying to figure this out. I have to charge the battery every time I want to take it out and am always worried it's going to die when I'm on the road somewhere. Grounds are all good. Engine cranks well.

Any help would be appreciated.

Thanks,
Andy

 

[vwnate1]

Hi Andy ;

I wish I was there as I know how to diagnose it in person, maybe there's a ground strap gone loose or corroded under neath the bolts holding it ? .

 

[Chiro]

I know you would Nate. The grounds are all good. Engine cranks like a b*tch in heat. Initially thought it was a ground as well. Ran a wire from the case of the generator to the Neg. terminal of the battery as a test and no change for the better. Pretty sure that the new Chinese VR is no good. How can I test that in the car? Additionally, I checked all the wire terminals. They are all good and tight. Everything LOOKS good but no charging.
Andy

 

[Bill Hanlon]

Not knowing what generator it is or what regulator the Chinese have copied, I'd start with the "operational checks" on this page 1955 - 1959 GMC Trucks Maintenance Manual - Models 100 - 500 of the 55-59 GMC Maintenance Manual. At the bottom of each page there is a "previous page" and a "next page" arrow that will get you pack into the generator section and forward into the regulator section. You can probably ignore the "dual contact" regulator as it was used on big trucks.

 

[coilover]

Andy, it has been years since a project left the shop with a generator on it but a couple of $.02 cents of suggestions. First do a search on "electronic regulators" for 12v generator and see if one matches your need. Just bolt on and run---no skills needed which is good since ones that know how to adjust a regulator are getting scarce. The second is back in the 60's/70's we use to use the Chrysler one wire regulator that varied the power to the field to regulate charge amount. This may have worked only with alternators, your generator guy might know. Picture shows a FRACTION of the starters, generators, and other components left over from 6v to 12v conversions or even full size to mini units. Most got thrown in the scrap bin.

 

[vwnate1]

Andy ;

Follow the shop manual tests, disconnect the wires from the generator, fire it up and let it idle and look at the voltmeter .

DO NOT MINDLESSLY REV. THE ENGINE TRYING TOMAKE IT CHARGE ! .

It will either charge or not, you can try full fielding it, follow the instructions, IIRC you apply power to the field terminal to full field these BUT CHECK FIRST ! .

If it shows any charge no matter how slight, gently raise the RPM's as you keep a weather eye on the voltimiter and STOP before it reaches 12 volts because it'll overheat and ruin the generator before you can say oh, $#it .

Let us know what you find .

Apparently I'm no longer getting notice of replies =8-( .

I'm using an electronic voltage regulator on my 1959 Nash Metropolitan's generator and I love it !~ longer brush life and *perfect* charge rate 24/7 night or dark, tube radio and wipers on or not...

The mail thing is : you have to match the regulator to the generator's field circuit~ typ "A" or "B" .

One grounds the field circuit to induce charging, the other powers it for the same effect, cannot be exchanged .

 

[morabuffalo]

I remember some systems that you always had to polarize the regulator...Nate, is that what that is. It would at times lose that polarizing for no good reason and sometimes at very inopportune moments. I actually forget which wire had to go where to polarize for a very quick spark...very quick!

 

[vwnate1]

NO ! .

'Polarizing' is ONLY DONE after the job is buttoned up and only if it doesn't charge ! .

Yes, you're correct it only takes a 100th or a second spark more and you're liable to fry the points in the regulator .

"Full Fielding" is where you have the generator disconnected from the voltage regulator ("Control Box" for our English friends ) and you then test the generator in a basic and simple good/bad test ON THE ENGINE by driving it to it's full output were it can and will self damage if you're not careful .

Then there's "Motoring" a generator, done on the bench to see if you replaced the brushes and didn't screw it up (or, to easily test junkyard / swap meet parts) .

FWIW, I've gotten plenty of bad 'rebuilt' generators right out of the box .

 

[Chiro]

Update. I polarized the generator by doing the "flashy" thing between the BATT and FIELD terminals at the voltage regulator. Took it for a looong drive and it's now charging. Gets up to 13 volts as needed at speed, then settles in at just over 12 volts according to gauge in car. Thanks guys.
Andy