6 Volt Generator Charging Problem
Cross-Country
Joined: Nov 2016
Posts: 68
Likes: 7
From: Minnesota
Thanks
Parts Nerd Extraordinaire
Joined: Sep 2010
Posts: 4,383
Likes: 1,791
From: Western NY
Let's back up...
You do know that it isn't a given that the AMP gauge will always show a charge indication. This can be true if the battery is actually charged up.
Which generator do you have? The 36 Amp C8BA, the 40 Amp 8EL, the 60 Amp 8BA? Do you have the matching regulator the C51A-C, the 8BA, the C8BAS (or equivalents)? If you are unsure, provide us pictures, part numbers, receipts, links - whatever you may have to help us identify what we are specifically dealing with and help build an efficient troubleshooting tree for you.
You do know that it isn't a given that the AMP gauge will always show a charge indication. This can be true if the battery is actually charged up.
Which generator do you have? The 36 Amp C8BA, the 40 Amp 8EL, the 60 Amp 8BA? Do you have the matching regulator the C51A-C, the 8BA, the C8BAS (or equivalents)? If you are unsure, provide us pictures, part numbers, receipts, links - whatever you may have to help us identify what we are specifically dealing with and help build an efficient troubleshooting tree for you.
Fleet Mechanic
Joined: Sep 2010
Posts: 1,835
Likes: 467
From: Mason City, Iowa
Let's back up...
You do know that it isn't a given that the AMP gauge will always show a charge indication. This can be true if the battery is actually charged up.
Which generator do you have? The 36 Amp C8BA, the 40 Amp 8EL, the 60 Amp 8BA? Do you have the matching regulator the C51A-C, the 8BA, the C8BAS (or equivalents)? If you are unsure, provide us pictures, part numbers, receipts, links - whatever you may have to help us identify what we are specifically dealing with and help build an efficient troubleshooting tree for you.
You do know that it isn't a given that the AMP gauge will always show a charge indication. This can be true if the battery is actually charged up.
Which generator do you have? The 36 Amp C8BA, the 40 Amp 8EL, the 60 Amp 8BA? Do you have the matching regulator the C51A-C, the 8BA, the C8BAS (or equivalents)? If you are unsure, provide us pictures, part numbers, receipts, links - whatever you may have to help us identify what we are specifically dealing with and help build an efficient troubleshooting tree for you.
So it looks like his generator works.
The voltage regulator sounds either bad or way out of adjustment. But that's just my 2 cents.
EDIT:
You are right about AMP gauge not showing a charge on a fully charged battery.
Maybe we should ask the OP what voltage he was seeing across the battery after he hooked everything back up and reved the engine up. Hopefully over 7 volts.
Last edited by hooler1; Mar 25, 2026 at 12:24 PM.
Parts Nerd Extraordinaire
Joined: Sep 2010
Posts: 4,383
Likes: 1,791
From: Western NY
Yeah, trying to get back to square one and get a good known foundation and then smartly navigate a troubleshooting tree rather than just chopping the tree down and throwing random branches out.
Cross-Country
Joined: Nov 2016
Posts: 68
Likes: 7
From: Minnesota
Cross-Country
Joined: Nov 2016
Posts: 68
Likes: 7
From: Minnesota
Let's back up...
You do know that it isn't a given that the AMP gauge will always show a charge indication. This can be true if the battery is actually charged up.
Which generator do you have? The 36 Amp C8BA, the 40 Amp 8EL, the 60 Amp 8BA? Do you have the matching regulator the C51A-C, the 8BA, the C8BAS (or equivalents)? If you are unsure, provide us pictures, part numbers, receipts, links - whatever you may have to help us identify what we are specifically dealing with and help build an efficient troubleshooting tree for you.
You do know that it isn't a given that the AMP gauge will always show a charge indication. This can be true if the battery is actually charged up.
Which generator do you have? The 36 Amp C8BA, the 40 Amp 8EL, the 60 Amp 8BA? Do you have the matching regulator the C51A-C, the 8BA, the C8BAS (or equivalents)? If you are unsure, provide us pictures, part numbers, receipts, links - whatever you may have to help us identify what we are specifically dealing with and help build an efficient troubleshooting tree for you.
As for the regulator this is the one I bought
https://www.dennis-carpenter.com/tru...YaAjojEALw_wcB
Last edited by Lando25; Mar 25, 2026 at 03:17 PM.
Parts Nerd Extraordinaire
Joined: Sep 2010
Posts: 4,383
Likes: 1,791
From: Western NY
That is generally a viable generic voltage regulator, but it may need to be adjusted as they don't necessarily come tuned for your specific generator. Instructions are in the service/shop manual. You should get one if you don't already have one!
Cross-Country
Joined: Nov 2016
Posts: 68
Likes: 7
From: Minnesota
Thanks for the info, I have both the F1 and F47 shop manual and have glanced at the regulator maintenance section. I'm guessing the shop who looked through the generator never actual adjusted the three regulator circuits like they said they did. Between my ohm meter and amp clamp I should hopefully be able to get it tuned correctly.
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Cross-Country
Joined: Nov 2016
Posts: 68
Likes: 7
From: Minnesota
More Turbo
Joined: Mar 2004
Posts: 716
Likes: 78
From: Salem
What year is your truck? Does it have a junction block where many of the wires connect? If yes, spend some time tracing wires to be sure all is connected correctly.
I had this problem - a couple wires crossed, then straightened out and the battery charged perfectly.
I had this problem - a couple wires crossed, then straightened out and the battery charged perfectly.
Fleet Mechanic
Joined: Sep 2010
Posts: 1,835
Likes: 467
From: Mason City, Iowa
Just a quick question on your Amp Clamp. Is it rated for DC? Many of them, the more consumer types you'll find at the Home Depots, Lowes, etc aren't. Sorry for the question but I was kind of curious.
Also as the engine is running are you seeing any voltage at all on your Armature and your Field terminal?
Thanks!
Also as the engine is running are you seeing any voltage at all on your Armature and your Field terminal?
Thanks!
Fleet Mechanic
Joined: Sep 2010
Posts: 1,835
Likes: 467
From: Mason City, Iowa
Just a quick question on your Amp Clamp. Is it rated for DC? Many of them, the more consumer types you'll find at the Home Depots, Lowes, etc aren't. Sorry for the question but I was kind of curious.
Also as the engine is running are you seeing any voltage at all on your Armature and your Field terminal? And if you measure for voltage between the Armature and the Battery terminal at the voltage regulator what do you get?
Thanks!
SORRY about the double post! I thought of another question and accidentally added it to a double post.
Also as the engine is running are you seeing any voltage at all on your Armature and your Field terminal? And if you measure for voltage between the Armature and the Battery terminal at the voltage regulator what do you get?
Thanks!
SORRY about the double post! I thought of another question and accidentally added it to a double post.
Last edited by hooler1; Mar 26, 2026 at 07:14 AM.
Cross-Country
Joined: Nov 2016
Posts: 68
Likes: 7
From: Minnesota
Just a quick question on your Amp Clamp. Is it rated for DC? Many of them, the more consumer types you'll find at the Home Depots, Lowes, etc aren't. Sorry for the question but I was kind of curious.
Also as the engine is running are you seeing any voltage at all on your Armature and your Field terminal? And if you measure for voltage between the Armature and the Battery terminal at the voltage regulator what do you get?
Thanks!
SORRY about the double post! I thought of another question and accidentally added it to a double post.
Also as the engine is running are you seeing any voltage at all on your Armature and your Field terminal? And if you measure for voltage between the Armature and the Battery terminal at the voltage regulator what do you get?
Thanks!
SORRY about the double post! I thought of another question and accidentally added it to a double post.
Cross-Country
Joined: Nov 2016
Posts: 68
Likes: 7
From: Minnesota
The truck was restored 5 years ago and it has never charged since then so this might be the issue too. I didn't wire it, but we bought a new harness and it's about as simple as it gets so I'm not sure where it could have gotten crossed up at.
Fleet Mechanic
Joined: Sep 2010
Posts: 1,835
Likes: 467
From: Mason City, Iowa
If it says AC/DC its probably good.
Something else I was thinking about. Last summer I was helping a friend out with his. After was got things straightened out and charging again I took a voltmeter and measured what voltage we had from Field to ground while it was running and charging. If I remember correctly we saw a little over 4 volts.
Another thing, inside or under your voltage regultor there should be 2 wire wound resistors connected to the Field terminal, one to ground, and the other connected to the Armature terminal. Are they both there and neither one of them burned up? If you disconnect all the wires from your regulator, you should see some
Sorry for all this stuff. Its just rattling around in my mind!
EDIT:
Correction;
You should see some continuity with an ohmmeter between the ARM and Field Regulator terminals. If you see an open, that is a problem.
Last edited by hooler1; Mar 26, 2026 at 05:32 PM.