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my earlier posting on this subject was vaporized by the server changeover..

I am showing a discharge on my ammeter in my 56, no matter what the revs. the more load i put on the system (lights, blower fan, etc), the deeper the discharge - as expected. I cannot get the ammeter to return to the center or show a charge. I have done the following:

1) tried 2 different generators, both recently rebuilt, and both pass the motoring test (no change in behavior).

2) tried 3 different regulators after properly polarizing (no change in behavior).

3) checked wires from generator to regular terminals for continuity - good.

4) ran separate ground from generator case to regulator case (no effect)

5) ran separate ground from battery negative terminal to regulator case (no effect)

6) truck has been rewired top to bottom and all electrical systems work properly

Observations: Battery voltage (engine off) is 12.6v and does not change when engine is running. putting on high-beam headlights only drops voltage to 12.55. I have had this battery on a tender for a couple of years so it is fully charged.

the only part of the system i did not switch out is the battery itself.

i am virtually certain i have seen the system work properly months ago before the truck was finished, but i am questioning myself on this observation.

any ideas about what could be wrong here? will the regulator not cut-in until the battery voltage drops to a certain value? Will the system begin charging once the battery discharges a bit? can a battery be "overcharged'?

I'd suspect you've got the wires reversed on the ammeter terminals

Bill

Hy tomctomc, It sounds like a regulator issue to me, running the igniton is not a heavy load and might not trigger the regulator to charge a battery that has been maintained, however by starting the engine you have just put the heaviest drain possible on the battery, so the regulator should cut in to replenish the battery. Loads such as the headlights should definately trigger the regulator. I would take the regulators/truck to a good automotive electric shop and have them checked out, hope that helps.

thanks for your thoughts... i am pretty sure i do not have a wiring error, but let me tell you what i have:

blue from gen F terminal on Generator to lowest lug on regulator, "FLD". Brown from A terminal on Generator to middle lug on regulator "GEN".

I imagine that eventually i will have to take it to a pro, but i am an electrical engineer by profession, and i do understand generally how this is supposed to work. However electro-mechanical parts like this original-style regulator is a design a bit before my time! I sure would like to figure this out for myself.

you've got that part wired right, A to A [armature], F to F [field] - if different generators and different regulators result in the identical behavior, what's left? wiring someplace is wrong, check the ammeter wires again

Bill

Bill - that's where i am at in my thoughts as well. but the wiring is very simple. Black from Battery to one side of the ammeter, red from other side of ammeter to BAT terminal on regulator (which continues on to horn relay). not much to go wrong there. when a load is put on the system, the proper discharge is shown on the ammeter. with the engine running, no charge is indicated - and I believe it because the voltage back at the battery never changes. it stays at 12.6v.

i am going to ground the field terminal to prove the generator produces in excess of ~13v. if it does, i am going to concentrate on the regulator.

I searched the forum back 15 years and "failure to charge" problems come up a lot. its usually a regulator problem, so that also makes me think my problem is there...

thanks for your reply.

Good choice on the field grounding- - - - -just don't run the RPM up a lot because there will be no voltage control. Was the generator polarized properly after installing it? After polarizing, there should be at least 1/2 volt present at the Arm. terminal of the generator with the engine running and no wires connected to the generator at all. This is called "residual voltage" and it's what the field coils use to begin the charging cycle. That voltage is sent through the regulator points to ground, and the voltage rises until a preset current flow or voltage is reached. At that stage, either the curreulator OR the voltage regulator points begin cycling several times a second to control the field current. Make sure the spring-closed points are clean, but DO NOT file or sand them. A piece of clean index card or business card stock makes an excellent cleaning medium. It's abrasive enough to clean oxidation off the solid silver points without scratching them. Once the charge current drops below the max setting of the points behind the ARM wire, they stay closed and the voltage regulator points (behind the FLD wire) start to cycle. The third set of points, the cutout relay which is in line with the BAT wire of the regulator, is open with the engine off, closes when the generator voltage rises 1/2 volt or so above the battery terminal voltage, and stays closed until the engine is turned off.
Jerry

thanks Jerry for your thoughts. I did polarize it (or attempt to) - but the question is "properly"? I don't know.. i kept the jumper connection for only 1/2 second or so... perhaps that was too short? no harm in doing it again. i will try the 'no wire' test on the generator.

as far as the regulator - two of them are essentially new. should be no problem with cleanliness of the points. i tried a 3rd, an old one that came with the truck when i got it in 2006.. it looks a little more "used", but not bad. however it didn't correct the problem either.

this problem has me puzzled.. everything is new/replaced and the system stubbornly refuses to charge. I hope the field-grounding test confirms the generator is good - and i suspect it will because it spun fine when tested as a motor.

Tom

I would start at the generator. With the engine running and the armature lead removed, ground the field at the generator and observe the voltage on the armature. It will be 20 volts or more. Make sure that it is the proper polarity. If that test is successful, replace the armature wire and measure at the regulator. I will wait to see what happens.

It's not necessary to remove any wires to ground the field- - - -just run a short jumper from the generator field post to ground. If the voltage at the armature post goes up, try the same field-grounding procedure at the regulator and check the voltage at the regulator ARM terminal.
Jerry

Jerry,
my suggestion of removing the armature wire was to allow testing of the generator without any other influences. I thought this might take some of the mystery out of the situation.

The only time I run a generator with the wires disconnected is when I'm checking for residual voltage. Grounding the field with nothing connected can cause a major voltage spike- - - -30+ volts in a matter of a second or two. Once the battery gets into the circuit after the cutout relay closes, it acts like a shock absorber to dampen out big voltage swings.
Jerry

I will run the tests(s) later today and report back. Is there any mechanism where the generator would pass the motoring test and yet fail as a generator? thank you for the help.

Tom

I would say that if the generator was polarized backwards, that would be the case. I think this could happen if one were to motor it with the polarity reversed. By the way I have never tried this.

OK - first piece of data: the "no leads connected" generator test showed the generator putting out 16V and headed up when the field terminal was grounded. Same behavior at the regulator - as expected as the wiring is new. looks like my generator is good. its hard for me to believe that i got 3 bad regulators, but i will focus my attention on that part. by the way - what is the proper Delco Remy part number for the Voltage Regulator? i have the the 25A generator. i think i want to go OEM with the next regulator I try...

It looks like any of the following D-R regulators will work:

Output Amperage:36-42
(Edit: The current regulator can be adjusted to work with the 25-amp generator on any of these. Jerry)

Application: Delco Generators

Buick 1955-62, Cadillac 1955-62, Chevrolet 1955-62 Equiped With Delco Generator

Reference Numbers: Delco 1118277, 1118337, 1118338, 1118389, 1118739, 1118740, 1118745, 1118885, 1118886, 1118887, 1118888, 1118889, 1118890, 1118929, 1118930, 1118948, 1118973, 1119004, 1119163, 1119266, 1119275, 1119600, 1119602, 1119609, 1119610, 1119623, 1119627, 1119629, 1119630, 1119633, 1119637, 1119638, 1119639, 1119640, 1119648, 1119654, 1119655, 1119660, 1119661, D619, D623, D625, D627

My mid-1950's Delco-Remy service bulletin book lists the #1118825 regulator as the standard replacement item for regular-duty 12 Volt generator regulators. I'd also reccomend using an original-equipment Delco regulator, not one of the repops from overseas!

Edit #2: There are literally dozens of NOS Delco-Remy regulators on ebay right now, with various applications listed. Any of them can be adjusted to match your 25-amp generator, so don't automatically reject one that lists a 35-42 amp rating if the price is right. It's a simple spring tension change on the coil behind the ARM wire. It will make no difference at all where the max voltage setting is concerned.
Jerry

I know this may sound stupid, but did you bring the RPMS up with the gas as you were checking both charge and voltage? The generator will typically not charge at low idle.

When I got my wiring harness, the schematic was incorrect and had the amp meter hooked up backwards.

I have also had odd thing happen with old batteries where they would not show a charge at the gauge. I would for sure borrow a known good battery from your car and try that before I did anything else.

Kurt

There are some really lousy-quality imported regulators on the market now, so getting three bad ones in a row doesn't surprise me. Have you had any of them apart, at least removing the cover? Some of the repops are actually solid-state items with few, if any mechanical parts, while others are just cheap-quality mechanical regulators with springs and points inside like the originals. Some of those will respond to adjustments, but it's better to start with a good-quality original-equipment item.
Jerry

Kurt - yeah i had the rpms up.. no dice. the ammeter shows proper discharge when the lights or other load is turned on. I know i am not charging because the battery voltage doesn't change with the engine on or off.

Jerry - these are cheesy looking mechanical repops.. i am going to get a OEM Delco Remy... i bet that does the trick.

thanks for keeping the ideas coming.

Bill wins - there was indeed a wiring problem. i checked for continuity from the generator to the regulator, and it was (apparently) there. what a continuity check won't show you is if there is a short in the path. i read 0 ohms from the armature wire at the generator to the other end at the regulator, implying a complete circuit. I decided to read the resistance to ground of the armature wire and found that there was also 0 ohms from each end to ground. The wire was pinched under a bolt on the firewall shorting it out. when i repaired the short, the charging system returned to proper operation. thanks for all the help.

Tom

Well that is good news. It is nice when a really tricky problem gets solved!

Glad you found it! I'm surprised the generator didn't destroy itself by charging straight to ground, unless the short also killed the residual voltage and never let the initial charge get going. You get an A+ for being persistent and finding a non-standard problem. A lot of folks would have scrapped the whole system and installed an alternator!
Jerry

thanks for the reply.. i was wondering myself why i didn't fry the generator - i think the dead short did prevent the generator from getting its original charge up. I have the window-washer set up in my truck, the wiring short was behind the glass bottle and was not apparent until i removed the bracket and looked over every bit of the wiring..

window washer

so, yeah, i had to be persistent to run this one down