D-15 Voltage Regulator

1) Did you Polarize the new genny??? If not try that n see what happens.

2) Is she wired correct??

BAT on VR wires up to the ammeters Load (NOT to battery/starter) terminal ARM (or GEN) on VR wires to gennys Arm post

FLD on VR wires to gennys Field post

3) For the genny to get to n charge the battery it must have a current path !!! If so and the VR is wired correct the BAT terminal on the VR MUST ALWAYS READ HOT BATTERY VOLTAGE. If it dont, make sure a wire from it gets up to the ammeters load (NOT to battert/starter) terminal.

4) If wired correct and good, BOTH the ammter terminals MUST ALWAYS READ HOT BATTERY VOLTAGE, do they??? Thats the path for the genny to charge the battery,,,,, ,from the gennsy ARM post,,,,,to the VR,,,,, through the VR to the VR BAT terminal,,,,, ,,to and through the ammeter,,,,, ,,,to the battery often via the big cable on the starter solenoid or switch.

5) Is the VR suitable for your ground????

Polarize her,,,,,mkae sure the VR to genny is wired correct,,,,, ,,make sure the VR's BAT terminal is always hot,,,,, ,,,,make sure BOTH ammeter terminals are always hot,,,,, MAKE SURE BOTH THE GENNY AND VR HAVE A GOOD GROUND !!!!!

Lemme know and if still no charge I will post back more troubleshooting tips to see if its a VR or a genny problem. Does the ammeter work and what does it indicate from setting to wide open??? Youre correct, if shes charging the battery voltage should rise from 12.6 to over 13 volts at wide open.

Lemme know, good luck n God Bless

John T A D 15 owner and retired electrical engineer

I wonder if your generator and voltage regulator are compatible. Click on one of Soundguy's responses and email him direct to sort that out. I believe he will be able to identify which regulator and generator that you have. After 40 years of messing with generators, every job is a learning experience for me.

John T

Still.. napa should have provided the correct part..

Soundguy

If the wire wound bias resistor is connected from ground tab to field tab.. then it is a A circuit regulator. If the resistor is between the ARM tab and the field tab, then it is B circuit. ( Note.. some B circuits will have an extra resistor as well.. )

Soundguy

I think this may be why I had a problem recently. It was a Ford 2N. The owner had bought a new generator and regulator. I polarized the generator for positive ground. The generator would not charge. I jumped battery voltage to the field and the generator charged great. I tryed everything to get the regulator to push some voltage to the generator but no luck. It seemed to me that the regulator was controlling ground current rather than controlling voltage to the field. Supposedly from the box, the two were supposed to be compatible. So he bought a new regulator and same result. Could be the regulator was right but the generator was wrong. Anyway after hours of frustration, I hooked voltage up to an ignition ballast resistor and ran it to the field. Generator works fine and voltage is always below 13.8.

From my description, can you tell what was going on?

8n came with a '3 wire' 2 brush genny. and was "A" circuit. Used a 4 terminal vr. The field was internally hot.. that is, tied to armature. VR controlled field ground via a vibrating contact. To get max charge, you 'full fielded' the genny, by jumpering ground to the field tab. This provided max power to the field and bypassed the vibrating field contact that grounded the field tab when vibrating.
Polarizing this system was accomplished by jumpering armature to battery.. do this with engine OFF. Full field by jumpering ground to field tab.

NAA and up used a "B" circuit genny and vr. Field coil in genny was internally grounded, and field current was supplied by the vr to the field tab. You full fielded this genny by jumpering bat to field. This provided max field power, and bypassed the vibrating field contact. Interestingly enough.. this is also a method to polarize this system. Polarize it with the engine off, and then with engine on.. you can full field it.

If you check the repair manuals, they will tell you how to do a motoring test on a genny. Most gennies that will 'motor' will also charge.

Essentially you are pulling the belt of, and bypassing the arm/bat cutout, and then powering the field or grounding the filed, depending on which circuit type you have.. then the genny should motor.

Sounds like you have a later B circuit genny from a NAA or hundred series, and were using the VR for an 8n. ( 8n and NAA vr are NOT compatible ). The a-circuit 8n vr would not provide field current to the B circuit genny.

Ideally, your workaround will provide minimum charge at idle, and not discharge, and yet, not overcharge at high rpm, thus reducing the life of your battery. unfortunatley.. a single resistor probably isn't doing this. Too high a resistor value and the genny won't charge at low rpm, and too low a resistor value, and the charge rate at high rpm may damage the genny eventually.. or the VR. My 8n genny can charge around 30a full fielded at 2200 engine rpm. It's only rated for 20-25.. so eventually that would kill it. The other issue is the cutout relay. Without a cutout, as soon as you shut the engine down, the genny can drain the battery. Did you keep the 8n vr grnd/bat/arm contacts hooked up, to use the cutout, and not hook up the field tab, and instead used a resistor from arm to field hookup to accomplish the work around? or are you using a manual battery isolation switch/ or a 2 terminal cutout relay?

On my IH cub, for years I used a 3 DPDT high current toggle switch as my charge control. center was off in that one side ( spdt) of the switch I wired it so the arm / battery contacts were open center, but closed on either side. On the other section for the switch (spdt), ground went to the common contact, and then from one side contact to the genny field was a low value resistor, and from the other side contact to the genny field was a high value resistor. What that yeilded was about a break even charge at idle on the low setting and about 4am charge at high idle, and with the switch in the other direction it provided a charge of about 4 amps at idle, and 11 amps at high idle.

This way I had a high, low and off charge setting.. usefull for either just running and slow charge onthe battery.. or running with lamps and charging the battery. I finally got off my duff and just fixed the oem vr so that it was back to 'auto-magic' working.. and no switch needed.

A naa / hundred circuit VR should fix you up.

Soundguy

As long as the battery voltage never gets above 7 volts, my jerry-rig circuit should keep him going. So far, it has been less than 7 volts even after mowing an hour.

Thanks for your help!