8n Ford Tractor Battery Discharging Problem

Jim R · Jan 25, 2016

I have a 1948 Ford 8n tractor. This is the first Ford I've ever owned. It's my chore tractor on my acreage. I have a problem with the battery discharging when the tractor sits overnight. It is still a 6 volt Positive ground system. If I disconnect the positive battery cable when I shut off the tractor, then the battery stays charged. I'm electrically challenged, especially with this Positive ground system. Can any of you old Ford guys out there tell me where to check or what to look for?? Thanks for any advice!!

Jim R · Jan 25, 2016

Also when I am using the tractor, it always registers at least plus 15 to 20 amps. charge. It never goes back to close to 0, no matter how long I run the tractor. Thanks again for any advise!

Bruce (VA) · Jan 25, 2016

Positive ground doesn't have anything to do with the problem.

You have a bad v/r. Smack the cover a few times with a rubber mallet to try and unstick the points. If it works, buy a lottery ticket. If it doesn't, buy a new v/r. And be careful how you install it or you'll let the smoke out.
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greywolf224 · Jan 25, 2016

Curious just start happening or you just bought it this way?

Hard to tell since it may be wired differently than original but I would start at the key switch and make sure that it truly is shut off when you think it is.
Since you said its a 6V, I would guess you still have the original 2 post key switch. If so disconnect one of the wires and see if the battery drains. if it doesn't you have a bad switch.
If you have access to a voltmeter and know how to use it, check for voltage at either post of the switch when it is turned off.

Another thing comes to mind. Do you have lights? Do they work? Is the switch on?
Check the light switch same as above.

R Geiger · Jan 25, 2016

(quoted from post at 07:33:22 01/26/16) Also when I am using the tractor, it always registers at least plus 15 to 20 amps. charge. It never goes back to close to 0, no matter how long I run the tractor. Thanks again for any advise!

If the cutout relay is stuck like Bruce says, you should see a discharge when you shut the tractor off. If you tap on the VR and the amp meter goes to zero, then you have found your problem.

Jim R · Jan 25, 2016

The Voltage Regulator is only a few months old and was installed at a local Auto Electric shop, but I'll gladly check it out and let you know what I find. Thanks so much!

R Geiger · Jan 25, 2016

(quoted from post at 08:24:17 01/26/16) The Voltage Regulator is only a few months old and was installed at a local Auto Electric shop, but I'll gladly check it out and let you know what I find. Thanks so much!

I have had VR's not work right out of the box. Do not assume anything is good just because it is fairly new.

Dell (WA) · Jan 26, 2016

Jim.........positive (+) ground aintchur problem. Ittzchur square can voltage regulator underneath the oil pressure gauge. Carefully giver a smack with wooden handle screwdriver. Heck even a wooden branch would due. With all them electrons floatin' around, wood is better'n steel, eh? As Bruce sez, ittzchur cut-out relay inside the square can. Some times the pivots qitt buggered up, some times the square can isn't making good ground, re-tighten the mounting screws. Some of the very early square can voltage regulators were actually mounted on rubber baby buggy bumpers and surprize, rubber don't conduct electricity. While modern square can voltage regulator mount directly to the dash, they STILL need to be polarized. Just "arc-spark" the side-by-side BATT and GEN terminals together, engine OFF. I use a broad blade stubby screwdriver. You kenn use bailin' warr iff'n you want. Simple, eh? ...........HTH, electrical Dell

JMOR · Jan 26, 2016

(quoted from post at 04:45:54 01/26/16) Jim.........positive (+) ground aintchur problem. Ittzchur square can voltage regulator underneath the oil pressure gauge. Carefully giver a smack with wooden handle screwdriver. Heck even a wooden branch would due. With all them electrons floatin' around, wood is better'n steel, eh? As Bruce sez, ittzchur cut-out relay inside the square can. Some times the pivots qitt buggered up, some times the square can isn't making good ground, re-tighten the mounting screws. Some of the very early square can voltage regulators were actually mounted on rubber baby buggy bumpers and surprize, rubber don't conduct electricity. While modern square can voltage regulator mount directly to the dash, they STILL need to be polarized. Just "arc-spark" the side-by-side BATT and GEN terminals together, engine OFF. I use a broad blade stubby screwdriver. You kenn use bailin' warr iff'n you want. Simple, eh? ...........HTH, electrical Dell

Also when I am using the tractor, it always registers at least plus 15 to 20 amps. charge." Sure sounds to me like polarization is not needed.

souNdguy · Jan 26, 2016

well, that's half your problem right there. taking the N to an auto electric shop to replace a apple sized box that takes 2 screws to mount and has 3 or 4 wires on it.

1, do you see a drain on the ammeter when you shut down?

2, is the ammeter still wired net charge / discharge like it was when it left the factory? ( lights on, engine not running should make a negative deflection ).

If 'yes' to both questions, and removing armature wire from generator stops the discharge, hook it back up to see the discharge, and then whack the vreg side with a hammer handle. if it clears up it was a stuck cutout.

that may or may not be the end of it.

Post back.

DGinVT · Jan 26, 2016

I had the same thing happen on my '50 late 8N. I took the cover off the VR and dragged a coarse piece of paper thru the points. Can use a relay contact burnishing tool if you have access to one. With the cover off and tractor running, shut it off and watch the action of the relay controlling the charge circuit. This shud open up when engine is stopped. At low rpms you will see the amp meter showing a discharge as they(the generators) act as a short circuit to drain the battery.

Bruce (VA) · Jan 26, 2016

" This is the first Ford I've ever owned."

I forgot to ask...........

Do you have the manuals?

(see tip # 39)

If you don't, it's time to order them.
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Jim R · Feb 2, 2016

Well, guys, I finally got a chance to work on my 8n some more and it appears like my, nearly new, voltage regulator was sticking. I started the tractor and tapped on the outside of the voltage regulator with a wrench and have used the tractor several times since then and have had no more problems with the battery discharging when the tractor is just sitting and the ignition off. So far, so good! Thanks for all the advice and responses!

R Geiger · Feb 2, 2016

(quoted from post at 08:18:30 02/03/16) Well, guys, I finally got a chance to work on my 8n some more and it appears like my, nearly new, voltage regulator was sticking. I started the tractor and tapped on the outside of the voltage regulator with a wrench and have used the tractor several times since then and have had no more problems with the battery discharging when the tractor is just sitting and the ignition off. So far, so good! Thanks for all the advice and responses!

Thanks for the feedback glad it is working for you. I have one that I have to tap on the VR to get it to charge. It is a new one also or close to it.

8n Ford Tractor Battery Discharging Problem

Jim R

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Jim R

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Bruce (VA)

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greywolf224

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R Geiger

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Jim R

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R Geiger

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Dell (WA)

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JMOR

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souNdguy

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