The Stovebolt Site Forums The Shop Area The Electrical Bay Generator/Charging issues

Hello - I did a search and read HRL's troubleshooting techniques for a charging system that isn't working, based on the ammeter showing discharge when a load is turned on. However, I remain stumped. I have a 56 3100, restored, but as close to as-built as I could get it. So it has the original 12v generator and regulator. It will not charge, with the battery voltage staying steady at ~12.5v regardless of RPM. The generator passes the motor test, which of course polarizes it. When the engine is running, grounding the field terminal will cause current to return to the battery, also based on the ammeter indication. I have swapped out the regulator 4 times (I had 2 DELCOS, an Echlin, and a no-name regulator on the shelf). None of them made any difference. The regulator case is properly grounded. The wires from the generator to the regulator were bypassed with test leads to see if i had a bad wire - nope. Proper voltage appears at the BAT terminal of the regulator..

So - I do not know whats next, except I am not putting in an alternator

Have any ideas or anything I have missed?

What's the story on the wiring? Is it original or is it all new?

Try running jumpers from the VR to wherever they go and see if that changes anything. There could be a break in one of your wires inside the insulation., etc.

Thank you for your suggestion. The wiring is all new a couple of years ago (done by me). I did try the jumper idea, bypassing the existing wires to the A and F terminals from the regulator and nothing changed. There is solid battery voltage at the BAT terminal. It was working fine when stored for the winter and this spring I encountered this problem... its a real headscratcher.

Try running a ground wire from the base of the regulator to the generator housing. Sometimes the firewall sheet metal where the regulator mounts doesn't provide a good enough ground for the relatively low current it takes to operate the field circuit. Just a couple of ohms of resistance between the regulator housing and the generator field frame can mess up the regulator operation and result in a "no charge" situation.
Jerry

Thanks Jerry - I added that wire originally when I re-wired the truck and it is still there now (and the regulator case measures at 0.2 Ohm to the generator and any other good ground). So that is not the issue. I wouldn't bother the forum until I exhausted all avenues I could think of.. now I do not know what to do. I thought maybe the ammeter was faulty, but the voltage stays at 12.5 or so when the engine is running from about idle to 2000 rpms. Is there any condition with the generator spins during the motor test, but is still faulty?

I'm not doubting that the "motor test polarized it", but I've never heard that until now. It just takes a second and a piece of wire to do it the way the the maintenance says to.

worth a try! I figured since the ammeter does show charge if the F terminal is grounded I figured it is polarized...This situation is really starting to cheese me off i just ran across this article and am going to study it: http://www.navioneer.org/riprelay/The%20Navion%20Files/Delco_Remy_Generator_Regulators.pdf

It's possible that the cutout relay setting is too high- - - -failing to complete the circuit between the generator and the battery unless the field is grounded. That's a simple check for anyone familiar with servicing and setting DC regulators, but it's nearly impossible to explain with a keyboard. PM me for a phone number and I'll try to talk you through the regulator diagnostic and setting steps. It's not uncommon for even brand new regulators to need adjusting to work right. I've got a mid-1950s version of the manual you referenced- - - -very good information!
Jerry

Thank you for the offer. Its off to work for the week, so I will not be getting back to this problem until the weekend.

He's had 4 voltage regulators on it and the problem doesn't change even a little bit.

What are the odds that 4 VRs would all be suffering from a cutout relay set too high? I think the odds are pretty slim.

By all means, test for that but I think the problem lies elsewhere - probably the generator itself or the wiring/grounding.

I agree Otto - no way would 4 regulators all be bad. The generator does pass the motor test - but is that really a suitable test? I had it connected to a jump pack which can deliver a lot of current... could it work in that test but not in the truck? Also, ignored in this whole discussion is the battery.. Is there a battery state/condition which would exhibit the symptoms I am seeing?

I've also seen "rebuilt" generators and starters that were heavily painted or powder coated so well that the field housing and the end frames were insulated from each other. There's such a thing as being painted too well!
Jerry

Do you still have any of the "failed" regulators? If you can send me one (preferably a Delco-Remy) I can do a continuity check on it to see if it has any internal circuit problems. There's not likely to be anything wrong with a generator that will "motor' and also charge with the field circuit grounded. A properly polarized generator will produce about 1/2 to 3/4 volts at the armature terminal with all the wiring disconnected, running at a fast idle. That's called "residual voltage".
Jerry

Thanks for the continued assistance. I studied that Delco Remy manual and now understand how these things are supposed to work. I am an electrical engineer so I think I got it. I will try to bench check it myself this weekend, but if I am still stumped I will send one. I will also check the residual voltage per your suggested test. Following the schematic, it looks like the field terminal starts off grounded through both the voltage and current regulator contacts. Since I already know the generator charges with the field terminal is grounded directly, one or the other of those contacts is opening. Or something I assume is grounded - isn't...

The voltage and current regulators are in series with each other. They perform an either/or function. When charge current is high, the current regulator prevents overloading the armature when charging a very low battery. Once the internal resistance in the battery rises the voltage is controlled by the vibrating points behind the field terminal. If you have an oscilloscope, you can monitor a modified square wave at the field terminal by the open/closed action of the points- - - -several times a second. Try burnishing the CR and VR points with VERY fine wet/dry sandpaper (1500 grit) and alcohol, followed by a thorough scrubbing with a piece of a clean index card or a business card. The contacts are pure silver, and are VERY soft. DO NOT USE A FILE! They operate with a slight wiping action for self-cleaning, and file scratches will make them stick. With both points closed, the resistance between the F terminal and the regulator base should be almost zero.

You can simulate a fully charged battery by putting a 1/4 ohm resistor in series with the BAT terminal. I use four 1 ohm 1K watt ceramic resistors wired in parallel for that. Final voltage adjustment MUST be done against a fully charged battery to get a proper setting. Both current and voltage settings will drop slightly when the steel cover is installed- - - -better magnetic conduction. I've been doing this stuff for 65 years. "It's so simple even an electric train driver can do it!"
Jerry

Thanks again Jerry. When I get to the bottom of this, I will share with the group. Everybody always wants to know the resolution!

So I convinced myself that the problem must be bad grounds.. so I added grounds to the generator body, and regulator housing and returned them to the body and the battery.. nope: no charge. After 4 regulator changes and adding a ton of grounds, the generator was all that was left..I did have another one with the wrong pulley in my attic, so I got it and gave it the motor test. Spun on the bench just like the one in the truck did. I pulled the installed generator and swapped pulleys and spruced up the paint on the spare. I put it in and the charging system works as intended. And the generator I pulled STILL passes the motor test. So I am pleased that the system is working properly but vexed that no real cause was found. I guess I can chalk it up to an intermittent situation or maybe an internal loose connection within the generator.

Have somebody check the armature with a growler. There are only a limited number of diagnostic tests that can be done on an armature without that piece of equipment. I've got one stashed away somewhere- - - -haven't used it in years! Also, try checking the resistance of the field coils- - - -from the insulated brush to the "F" terminal on the generator housing with the armature removed or the insulated brush isolated from the armature it should probably read 5 ohms or so. NO continuity from the F terminal to the field frame. Check the resistance of the ground brush holder to the end frame- - - -there should be NO measurable resistance there.

www.ebay.com/itm/127092812276?

Jerry

Thanks Jerry!