6 volt positive ground with alternator

[Tom Bond]

Would anyone have a diagram handy for a 6 volt positive ground with alternator to upload here? Have my hard copy service manual on the way but won't be in till next week. The tractor has a pretty cobbled up wiring job I'm trying to get straightend out. One wire alternator is putting out 8.5 volts but it's not making it to the battery when running. Looks like a birds nest under the dash and I want to clean it up. It even looks like the PO is using oem VR as a terminal strip! It runs remarkably good. Voltage just not making it to battery to recharge, lights not working, etc.... Thanks!

 

[JMOR]

Post a picture of your positive ground alternator.

 

[Jim.ME]

Post a picture of your positive ground alternator.

It wouldn't hurt to include the model of the tractor along with the 6-volt positive ground alternator picture.

 

[Welding man]

We build 6 volt positive ground alternators all the time. I keep one on the shelf. GM alternator and a 6 volt positive ground conversion kit and about 30 minutes to do the conversion. That is what is on this one. Puts out 45 amps with ease.

 

[Sean in PA]

We build 6 volt positive ground alternators all the time.

Do you work for a company that does that?

 

[Welding man]

I own a welding and repair shop. We work on a lot of tractors, trucks and heavy equipment and do some tractor restorations. For those that want to keep a tractor 6 volt and need a generator or regulator we usually put a one wire on them.

 

[Sean in PA]

The only reason I can see to want to keep a tractor at 6 volts is for originality, but switching from a gen and VR to an alternator busts that theory. A 12 volt negative ground system is so much better, in terms of both cost and supportability in the modern vehicle parts market, as well as the stronger spark jumping in the proper direction on a gas engine. All gasoline powered vehicle and engine manufactures switched to negative ground because it was proven that it gives a better, stronger spark.

 

[JMOR]

The only reason I can see to want to keep a tractor at 6 volts is for originality, but switching from a gen and VR to an alternator busts that theory. A 12 volt negative ground system is so much better, in terms of both cost and supportability in the modern vehicle parts market, as well as the stronger spark jumping in the proper direction on a gas engine. All gasoline powered vehicle and engine manufactures switched to negative ground because it was proven that it gives a better, stronger spark.

Sorry, but the spark polarity is NOT dependent on the primary (battery) ground polarity.

 

[Sean in PA]

Sorry, but the spark polarity is NOT dependent on the primary (battery) ground polarity.

Then why are the primary posts of the coil marked + and -?

 

[wore out]

Then why are the primary posts of the coil marked + and -?

"why are the primary posts of the coil marked + and -?"

In my experience, typically, so guys can observe that they are marked, and still connect up the coil backwards!

(From the John Deere Manual FOS-20.)

 

[JMOR]

Then why are the primary posts of the coil marked + and -?

Not all are. Some are marked "BATT" and "Dist".....and if you want a neg going spark, you need to know what the particular coil came off of or was intended for. By that, I mean that if coil was for a vehicle with neg ground battery and marked +/- and you install it on a vehicle with Positive ground battery, the primary wire need to be reversed in order to have a Neg spark.. In the case of coils marked Batt and Dist, now Batt would go to distributor and Dist would connect to Battery. They work, but there is the small loss of primary voltage (~ 1/100 th ) in the output spark. In a perfect world, you use the coil intended for the vehicle with Pos gnd or the coil intended for the vehicle with Neg ground. Inside the difference is whether the primary and secondary windings are connected Start-to-start or connected start-to-finish. Or you could forget all the technicalities and do it empirically, changing connections until you get Neg spark as here.

https://imgur.com/XKkUTYL

 

[Sean in PA]

Not all are. Some are marked "BATT" and "Dist".....and if you want a neg going spark, you need to know what the particular coil came off of or was intended for. By that, I mean that if coil was for a vehicle with neg ground battery and marked +/- and you install it on a vehicle with Positive ground battery, the primary wire need to be reversed in order to have a Neg spark.. In the case of coils marked Batt and Dist, now Batt would go to distributor and Dist would connect to Battery. They work, but there is the small loss of primary voltage (~ 1/100 th ) in the output spark. In a perfect world, you use the coil intended for the vehicle with Pos gnd or the coil intended for the vehicle with Neg ground. Inside the difference is whether the primary and secondary windings are connected Start-to-start or connected start-to-finish. Or you could forget all the technicalities and do it empirically, changing connections until you get Neg spark as here.

https://imgur.com/XKkUTYL

So polarity does make a difference.

 

[wore out]

So polarity does make a difference.

Yes, COIL POLARITY makes a difference, battery polarity does NOT IF the coil is connected to match.

 

[JMOR]

So polarity does make a difference.

....maybe & sort of & a little
My thoughts are too big that YT won't let me post so many words, so you can find my thoughts here:

Dropbox

www.dropbox.com

 

[Sean in PA]

Yes, COIL POLARITY makes a difference, battery polarity does NOT IF the coil is connected to match.

So, if you reverse the polarity of the battery and charging circuitry, you need to reverse the polarity of the coil?

 

[JMOR]

So, if you reverse the polarity of the battery and charging circuitry, you need to reverse the polarity of the coil?

That is the simple andd accepted answer, but.......and there is always a "but" & that is that you really have a choice of reversing to obtain Neg spark or leaving it alone an having a Pos spark that is a few hundred volts higher, but even that depends on the coil internal connections............they are not all the same.

 

[used red MN]

This is a shot in the dark without knowing what tractor you have. The info I am giving you will need a little tweeking. Hopefully you are able to save “you” from yourself if you know enough about wiring to do the modifications to your wiring if the diagram does not show exactly what you need. A 6 volt positive ground alternator is a rare beast but they do exist. What I have for you is a link to a post by Tim D. RIP. I would direct you to the 2nd full wiring diagram from the bottom of his list for an 8N with a factory 6 volt positive ground. At the bottom it has a red box with “vintage tractor” in it. You will disregard all the wiring circuits that have to do with the generator and regulator. And the wire off the back of your alternator will connect to the bottom terminal of the ammeter. YT post with Ford wiring info

 

[Tom Bond]

Would anyone have a diagram handy for a 6 volt positive ground with alternator to upload here? Have my hard copy service manual on the way but won't be in till next week. The tractor has a pretty cobbled up wiring job I'm trying to get straightend out. One wire alternator is putting out 8.5 volts but it's not making it to the battery when running. Looks like a birds nest under the dash and I want to clean it up. It even looks like the PO is using oem VR as a terminal strip! It runs remarkably good. Voltage just not making it to battery to recharge, lights not working, etc....

Here's the picture of the alternator. Positive ground 1957 960. Sorry. Forgot that in original post. And a pic of the wiring mess that needs cleaning up too. Lot of loose and rusted connections. A bunch of crack, frayed and different gage wires as well. Will just take time and some new terminals, wires and some new switches for lights and key. Getting 8.4 volts out of the alternator. The wire off it connects directly to one side of the ammeter and the other side runs to the armature connection on the VR. Ammeter does read the 8+ volts when running. Nothing wired to the field terminal on the VR. Only 6.2 volts consistantly on the bat terminal of the VR no matter the rpm. Still can't believe how good this thing runs with this mess. Just have to figure out the charging issue.

 

[JMOR]

Ammeters do not read volts

 

[JMOR]

Ammeters do not read volts

I will have to work up a pos gnd alt diagram on a 960, but need to know if diesel or gas and if you are sure about the alternator pos/ neg.