Farm Equipment - Polarizing generator

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Polarizing generator

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=140982
Printed Date: 26 Apr 2025 at 4:25pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: Polarizing generator

Posted By: Njlynch1925
Subject: Polarizing generator
Date Posted: 31 Jul 2017 at 6:44pm

I have a 1953 Allis WD with the original 6 volt pos. Ground. It was charging until i replaced the battery. I am. Not sure how to polerize it. The Gen. has a cut out one wire going from cut out to in side the gen. The other wire from the cut out back toward the battery box then ther is only one post on the gen body back from the cut out that wire goes to the battery box as well . Any help would be great thanks

Replies:

Posted By: DougS
Date Posted: 31 Jul 2017 at 8:29pm

Is there a wire to F terminal on the generator? There should be. If so, touch that terminal to ground while the engine is running and see what happens. Someone will need to watch the ammeter while you do this. Do this first. If this works, check and make sure the instrument box is well grounded. If this doesn't work then run a wire from the battery negative and tap the other end to the A terminal on the generator while the engine is not running. A momentary tap is all you need.

Posted By: Njlynch1925
Date Posted: 31 Jul 2017 at 8:31pm

I am not sure which is the F or the A terminal as they ar not marked . I have two post that the cut out is attached to then one single terminal that sets back from that

Posted By: DougS
Date Posted: 31 Jul 2017 at 8:51pm

Wrong. There's your problem. I don't see how it ever charged in the first place. The A terminal would go to the cutout and the F terminal should run back to the light switch. You need to sort things out. Look more closely. The gen terminals may be marked but somewhat hidden by the paint.

Edit: Are the two terminals from the generator tied to a single terminal at the cutout or are there three terminals on your "cutout?"

Posted By: DanD
Date Posted: 31 Jul 2017 at 8:57pm

There are only two wires that go to the generator. As the other post said, from the A terminal on the generator to the cutout and then from the other post on the cutout to the ammeter. I don't remember how the cutout is marked..maybe A and BAT? Have to have those hooked up the right way as well. The other wire from the generator goes to the F terminal and it goes to the resistor on the light switch. The terminals on the generator are marked. Like the other post said, may just be hiding under paint.

Posted By: Gerald J.
Date Posted: 31 Jul 2017 at 10:19pm

Because the current in the A circuit is much larger than the F circuit usually the A circuit stud at the generator is much larger than the F stud, like 1/4 vs #8 pr #10.

Polarize the generator (also called flashing) by using a jumper wire from the Battery post of the cutout to the A post on the cutout or the generator. Do that before running the engine in case you installed the battery backwards.

Gerald J.

Posted By: Brian Jasper co. Ia
Date Posted: 02 Aug 2017 at 1:04pm

To polarize just jump across the cut out relay momentarily. Both posts are marked A or F. You might have to buff off the paint to find them, but they're there. Every tractor generator I've seen the posts are the same size. Do what Doug says and ground the F terminal at the generator and see if it comes alive.

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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford

Posted By: Joe DeLisle
Date Posted: 02 Aug 2017 at 8:49pm

Did you hook the new battery up correctly? the WD was a positive grounded system originally. what do you currently have...positive ground, or negative ground?

Posted By: Super44
Date Posted: 06 Aug 2017 at 5:45pm

I am kind of in the same boat. My C has not been charging because the cutout had a busted wire. I changed the cutout and still it was not charging so I went in search of info and landed here and signed up. After reading this thread I did the wire from the battery to the A post on the generator and Vaa Hoo it was charging---- for a while. Then the needle started bouncing and went to discharge. After about 10 minutes it started to charge again for a bit and then discharge. Is this normal?? I've had the tractor for many years as it has a woods mower deck under it that gets weekly use. I've just been putting the charger on it when I was done but I finally got tired of that dance.

Posted By: DougS
Date Posted: 06 Aug 2017 at 6:28pm

I'd speculate that the problem is in thw wire, switch or resistor in the F circuit. Probably a loose ground. Understand how the F circuit works: When the F terminal is grounded the generator puts out the maximum current. This output can be changed by adding resistance to this circuit. If you have an intermittent ground or loose connection the generator will behave as you described. This is why I told the original poster that his genny couldn't work as it was wired. The F needs to be pulled low, not high.

Posted By: Super44
Date Posted: 06 Aug 2017 at 7:11pm

Not sure what "F needs to be pulled low" means. When the tractor was running I tested the battery and got nothing. With the tractor off I got 6.32 volts at the battery. I am very new to this kind of issue!!

Posted By: DougS
Date Posted: 06 Aug 2017 at 7:22pm

"Pulled low" is electric speak for shorted to ground. Pulled high means connected to the voltage side. These can be done through a direct wire connection or through a component such as a switch, transistor, relay or whatever.

Posted By: Gerald J.
Date Posted: 06 Aug 2017 at 10:21pm

There are two ways for a manufacturer to wire a generator field, one connects one field wire to the A post and then grounds the field direct or through a resistor to control the voltage. the other connects one field wire to the generator shell to be grounded by the mounting bolts and then the regulator connects the field wire to the A wire direct or through a resistor to control the generator voltage. Generally AC used the first connection but other users of generators used the other connection.

With a working regulator the generator voltage should be 7.1 volts for a full charge. Lower means not charged, higher breaks down the water in the electrolyte requiring regular refills with distilled water.

Gerald J.

Posted By: Super44
Date Posted: 07 Aug 2017 at 7:26am

I checked all the connections and none seem to be loose.

Posted By: DougS
Date Posted: 07 Aug 2017 at 9:50am

Is the box with the ammeter and light switch grounded securely or is it only slipped into the holder?

ETA: Is the light switch itself secure in the box?

Posted By: Super44
Date Posted: 09 Aug 2017 at 2:13pm

The box was just slipped on but I cleaned it up and put in the screws. I re flashed it but still have discharge when running it.

Posted By: DougS
Date Posted: 09 Aug 2017 at 3:42pm

Short the F terminal to ground while the engine is running. Have someone watch the ammeter while you do this. If the ammeter shows that it is charging, the problem is still somewhere in the F circuit. Possibly the light switch resistor. If it shows a bigger discharge, either the battery somehow got installed as negative ground or the ammeter got wired backwards.

As a last resort measure the voltage on both sides of the cutout. If you're measuring 7-ish volts from the generator but not out of the cutout, your cutout is bad. If your generator shows nothing to the cutout, take the generator to a shop and have it checked.

One last thing: Is the cutout grounded securely to the generator?

Posted By: Gerald J.
Date Posted: 09 Aug 2017 at 8:25pm

Has the ammeter been replaced? Is it wired right? First test, turn on the ignition and lights without the engine running, it must show discharge. If not its wired backwards.

Gerald J.