charging system

Trying to repair the charging system on an AC D17. 12Volt-positive ground-2 brush generator and external regulator. Regulator has 4 posts--lights + batt + field are on the bottom front and there is an unlabeled post on the back(under side). The generator has A and F on it. There is a hot wire coming from the dash and a wire going to the F on the generator and a wire going to the A on the generator. I need to know how to polarize the generator and regulator(if needed). (positive ground) I then need to know how to wire the regulator to the generator. If I connect a hot wire to the A on the generator, it will drive the generator(with the belt loosened) in the same direction as it turns when the tractor engine turns it when running. Electrical work is my really weak suite. Can anyone help? thank you, gregjo1948

I believe you are working with a type "A" charging system with a Delco generator, here's a simple diagram of a very basic charging system.

If you don't a have a wire from the light switch at the regulator (or no lights) you can ignore the "L" terminal.

Polarize the GENERATOR by momentarily jumpering the "BATT" and "A" terminals at the regulator.

<img src = "https://i.imgur.com/YMfYAlM.jpg">

I'm pretty clueless too when it comes to 'electronics'. But I'd guess the points in the regulator are stuck together.My solution to charging issues is to convert to a delco one wire alternator system.Take cutters and snip/cut and yank . Then install one wire alternator. Run one wire from alt to amp gage. then from gage to battery.Done. You can even go directly from alt to battery. Pull power from amp gage to an ignition switch. Then to coil. Done wrap the whole thing in a neat,clean,sanitary harness.You will have reliable,trouble charging.If you want lights or other 'options',pull them from gage too.You need to run a separate ground wire from alt to engine block. Just grounding through mounting bolts somehow doesn't work well. I have no idea why.A one wire Delco from NAPA costs less than 60 dollars,plus the 15 dollar core.I've done probably 10 like that. The first 15+ years ago. Have never had a moments problem with any.

No lights....Can the generator be polarized by touching the negative battery post(positive ground) to the "A" on the generator? Do I need to polarize the regulator if I polarize the generator? Is the wire from the ammeter to the "Batt" terminal on the regulator a hot wire? Do I need to ground the regulator to the tractor?(frame--battery) Told you electrical is bad for me. I don't want to smoke anything. thanks, gregjo1948

"Can the generator be polarized by touching the negative battery post(positive ground) to the "A" on the generator?"

Yes.

"Do I need to polarize the regulator if I polarize the generator?"

No, voltage regulators in typical old automotive and tractor applications do NOT need to be "polarized". It is the GENERATOR that gets "polaried".

"Is the wire from the ammeter to the "Batt" terminal on the regulator a hot wire?"

Yes.

"Do I need to ground the regulator to the tractor?"

Yes, to function the regulator requires a GOOD ground to the frame and on to the battery.

If the wire from the ammeter to the "batt" is hot, will that make the wire going to the "A" hot and make the generator try to run like an electric motor?

(quoted from post at 15:55:18 12/12/19) If the wire from the ammeter to the "batt" is hot, will that make the wire going to the "A" hot and make the generator try to run like an electric motor?

Click to expand...

Not unless the "cutout" points are welded together, as DeltaRed wrote. Their purpose is to disconnect the battery from the generator at shutdown, or any time it quits charging.

With the battery disconnected (to prevent causing a short with the metal cover), visually check to see if the cutout points are stuck.

If the engine was previously started without first polarizing the generator after a battery polarity swap, or the generator was replaced or repaired, the result can be welded cutout points.

I will check the points but, the regulator is new.(never installed) Thank you guys for all your support. Tomorrow morning I'll put all your explanations to use. I'll post the results as to how it went. gregjo1948

Greg, I will try to take your questions one at a time here goes:

1)Regulator has 4 posts--lights + batt + field are on the bottom front and there is an unlabeled post on the back(under side)

On many 4 terminal VR's LOAD BAT and FLD are up top side by side while ARM is underneath (maybe unlabeled ?) or off in one corner all by itself.

They wire as follows: BAT on VR up to the Load (NOT battery/starter) side of ammeter, its always hot
FLD on VR to Generators FLD post
ARM on VR to Generators ARM post
LOAD/LIGHTS on VR feeds hot battery voltage to loads like lights and ignition typically via the IGN
or Light switches

2) The generator has A and F on it.

That's Armature and Field, wired per the above.



3) There is a hot wire coming from the dash

That may be the Load side of the ammeter, see 1, it wires to BAT on the VR

4) and a wire going to the F on the generator and a wire going to the A on the generator.

FLD on VR wires to gennys FLD post, ARM on VR wires to gennys ARM post


5) I need to know how to polarize the generator and regulator(if needed).

ONLY the Genny needs polarized, use a small jumper wire to momentarily flash jump from BAT on VR to ARM on VR
orrrrrrrrrrr jump from BAT on VR direct down to gennys ARM post and you should get a small spark

NOTE BOTH the genny and VR need good grounds to work !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

NOTE Polarize BEFORE starting lest you damage the VR !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

6) I then need to know how to wire the regulator to the generator.

See 1 above

7) If I connect a hot wire to the A on the generator, it will drive the generator(with the belt loosened) in the same direction as it turns when the tractor engine turns it when running.

IT SHOULD DO THAT That genny, a DC Motor, is basically the same as a DC generator. If its grounded and you apply hot voltage to the ARM post it should indeed spin if the brushes and armature and bearings are in decent shape

NOTE HOWEVER with the VR having hot voltage on its BAT (from ammeter) when the tractor isn't running the cutout relay (between BAT and ARM on VR) should be open so the genny does NOT spin. If that cutout relay was bad and permanent stuck closed THATS BAD

NOW for wiring and troubleshooting instead of guessing look at my Charging System Troubleshooting Procedure linked below aND post back any questions

John T
John Ts Charging Troubleshooting

Red, the poster stated " If I connect a hot wire to the A on the generator, it will drive the generator(with the belt loosened) in the same direction as it turns when the tractor engine turns it when running"

I don't see that as indicating the points in the VR are stuck ?????????????

If a hot wire is connected direct to the gennys ARM post and the genny is grounded IT SHOULD SPIN and that does not in my opinion indicate the VR has stuck points ????????????

But hey I'm an old and long retired and rusty electrical engineer and may be wrong grrrrrrrrrrr if so my bad please explain it to me Im never too old to learn I HOPE LOL

Take care red, best wishes and Merry Christmas

John T

Yo Bob, to your statement, "Not unless the "cutout" points are welded together, as DeltaRed wrote. Their purpose is to disconnect the battery from the generator at shutdown, or any time it quits charging."

He said if he connects a hot wire to the gennys ARM post it spins right?? To me IT SHOULD but I don't see that as an indicator the VR has stuck cutout points ??????

But hey Im as rusty as an old nail on this stuff grrrrrrrrrrr my bad

take care and Merry Christmas Bob

John T

See my post above, Polarize the GENERATOR (NOT VR) by momentarily jumping a Hot wire, such as from BAT on VR (assuming its wired up to ammeter) TO EITHER the ARM terminal on the VR orrrrrrrrrrrrrr direct to gennys ARM post, and YES BOTH VR and Genny need good grounds.

John T

If he connected a hot wire to the a on generator he already polarized it.

That's right Teddy

John T

Good question: "If the wire from the ammeter to the "batt" is hot, will that make the wire going to the "A" hot and make the generator try to run like an electric motor?

NOOOOOOOOO NOT NORMALLY UNLESS THE CUTOUT RELAY INSIDE THE VR IS BAD AND STUCK CLOSED.

The Cutout Relay between the VR's BAT and ARM is normally open and only closes once genny is spinning fast enough and producing sufficient voltage.

If alls well when the tractor isn't running the VR's cutout relay is OPEN so theres no hot voltage on its ARM terminal so the genny wont try to spin. BUT if the VR is bad and relay is stuck closed YES there will be hot voltage on the VR's ARM terminal which is wired to the gennys ARM post and it will try to spin like a DC motor.

The design is ONLY once a good working genny spins fast enough will the cutout relay close so the gennys output can get to and charge the battery......

Got it ??????

John T