12 volt Positive ground?

noweirdbeard · Dec 9, 2018

Hi y'all.
I've been looking all over old posts for some insight to this problem, but haven't found any answers. I sure could use some advice.

I just bought a house and it came with an old 8n side distributor tractor. Guy said it was running a year ago when he parked it.

I went to pull the old battery and was very confused when I saw the positive cable was ground. :shock:

It has a newer looking one wire alternator and the old battery looks to be a normal 12 volt.

Can it run like this? It must, but it gives me the creeps to hook a 12 volt battery up positive ground!
Everything I have read says you MUST go to a normal negative ground when you convert to 12 volts.

HFJ · Dec 9, 2018

welcome to YT, with or without a beard, however weird

u can have a 12v positive ground system. the catch is, it will fry a normal alternator. it's possible the alternator u have is 12 volt compatible.

all things considered, it's a better idea to go negative ground. only the alternator cares about polarity, everything else will be fine.

the first step, in my mind, would be to take that alternator to an auto parts store and have it tested. he said the tractor ran, but he didn't say it charged. either he got an alternator converted for positive ground use, or he fried that one.

HFJ · Dec 9, 2018

lol, sorry, senior moment. hopefully the alternator u have is positive ground compatible. pretty sure they're all 12 volt compatible :lol:

MNGB · Dec 9, 2018

Generally 12 v systems with an alternator are negative ground but now alternators can be gotten that are set up for positive ground, check to see if that's the case other wise it will not charge and the alternator maybe toast
GB in MN

noweirdbeard · Dec 9, 2018

Thanks guys! Sounds like I dont really have much to lose by putting a battery in and trying it. I didn't think about a special alternator, but that very well could be the case.
I will plan to rewire to negative ground in the future, but I would love to get this thing fired up.
I will post back after I try it.

Also thanks for the welcome!

MNGB · Dec 9, 2018

Disconnect the wire from the battery to the alternator (will be a heavy gage wire 1/4" stud) then get the engine running that way the alternator will not be hurt and you can have it tested to see if its a positive ground one or negative and if it good.
GB in MN

doublebass73 · Dec 9, 2018

There is nothing wrong with positive ground. A ground is nothing but a common connection, it's still DC and electrons still flow in the same direction regardless of the ground connection to the battery. If the alternator is wired positive ground I wouldn't hesitate to run it that way. It's a good idea to have it tested first though.

rvirgil_KS · Dec 9, 2018

Disconnect the charge wire from the alternator

Reconnect the battery as it was with positive to ground. Turn on switch but do not start engine. Which way does the ammeter needle swing? If it goes toward negative ammeter is wired for positive ground, if toward positive it is wired for negative ground.

You indicate side distributor. If positive ground the + post on coil should go to side of distributor. If negative ground -- post on coil should go toward distributor.

If you have a normal negative ground alternator and it was hooked up positive ground it should be fried and should drain the battery when it sets.

rvirgil_KS · Dec 9, 2018

"electrons still flow in the same direction regardless of the ground connection to the battery"

Actually the opposite is true. Positive and negative ground is like right hand and left hand threads on a bolt. On a bolt the nuts turn in opposite directions. With positive and negative ground current flows through the circuit in opposite directions.

JerryCPP(WA) · Dec 9, 2018

I have a '52 8N that had been converted to a 12 volt 10DN Delco (external regulator type,) and it IS positive ground. It has a small regulator, about 1 1/4" x 1 3/4" mounted to one of the bolts. From the regulator, the RED wire goes to ground; the GREEN and YELLOW wires go to the 2-contact plug in the back of the alternator; the BLACK wire goes to the "BATT" terminal; the WHITE is taped off and hangs loose; a wire goes from the BATT terminal to the ammeter. I'd never seen nor heard of such a thing, but it works. I hope this helps.

Bob · Dec 9, 2018

One more possible angle to this...

It is POSSIBLE for a lead acid car battery that is 100% discharged to be recharged in the reverse direction.

It is POSSIBLE you have a (-) ground 12 Volt alternator system and a reverse-charged battery was installed.

As ridiculous as this may sound to some that have not experienced it, it HAS happened.

doublebass73 · Dec 10, 2018

(quoted from post at 15:08:51 12/09/18) "electrons still flow in the same direction regardless of the ground connection to the battery"

Actually the opposite is true. Positive and negative ground is like right hand and left hand threads on a bolt. On a bolt the nuts turn in opposite directions. With positive and negative ground current flows through the circuit in opposite directions.

DC only flows in one direction. If we are talking about electron flow that's negative to positive. If we are talking conventional flow that's positive to negative. For the sake of argument let's use electron flow (negative to positive). Whether I connect the ground to positive or negative, electrons are still leaving the negative terminal of the battery, flowing through their respective circuits then returning to the positive terminal of the battery. That was the point I was trying to make. The OP seemed like he was under the impression that positive ground was inherently bad which is not the case and the reason why I made the statement that electrons flow in the same direction regardless of the common connection point (ground).

I understand that certain devices have polarity requirements which is why you can't swap battery terminals willy nilly but that doesn't change the fact that DC only flows in one direction. Otherwise it would be AC.

rvirgil_KS · Dec 10, 2018

?Whether I connect the ground to positive or negative, electrons are still leaving the negative terminal of the battery, flowing through their respective circuits then returning to the positive terminal of the battery. That was the point I was trying to make.?

Thanks, I see your point now. Though these boards are most helpful there is always the problem ?what one guy thinks he read is not what the other guy thinks he wrote?.

Here?s a diagram to illustrate the question. You are right in that current flow is the same in regard to the battery regardless of ?ground? connection, that is from Neg post of battery through circuit to Pos post of battery. I was thinking in regard to direction of current flow through the circuit loads being opposite direction.

doublebass73 · Dec 10, 2018

Yes, you're right about current through the loads being opposite when you switch the grounds. That's a good diagram, hopefully that makes sense to the OP.

I did a quick search and found a few sources for 12V positive ground alternators so there's a good chance the OP has one. Here's one place that does them - http://www.qualitypowerauto.com/item_135/Positive-Ground-12-Volt-Alternator.htm

noweirdbeard · Jan 14, 2019

Just wanted to update you guys on the old tractor.
I started tracing wires and it was a mess. The alternator that was on there was a one wire and was going to the original voltage reg. There were bare wires and it was just a mess. I don't think there was anyway it was working properly before.
I bought a rewire 12 volt neg. ground kit. I replaced the points and condenser, coil and cap and rotor.
Got her to fire up this afternoon. She wont run for long, but I pulled the carb and its full of junk and water. Im going to address the fuel system and go from there. Looks like electrical is good to go. Thanks again for the help.

HFJ · Jan 14, 2019

good to hear. thanks for the update

JMOR · Jan 14, 2019

(quoted from post at 16:18:36 12/10/18) Yes, you're right about current through the loads being opposite when you switch the grounds. That's a good diagram, hopefully that makes sense to the OP.

I did a quick search and found a few sources for 12V positive ground alternators so there's a good chance the OP has one. Here's one place that does them - http://www.qualitypowerauto.com/item_135/Positive-Ground-12-Volt-Alternator.htm

ctually, current direction did not change because of where the circuit was grounded (positive or negative), but rather because of how you installed the battery. The same, I say, applies whether any part of the circuit was grounded or whether the circuit is totally isolated from ground. Word usage is everything!

Dollar Bill · Jan 15, 2019

You indicate side distributor. If positive ground the + post on coil should go to side of distributor. If negative ground -- post on coil should go toward distributor.

Not intending to be a S/A, only for posterity....

On a NEGATIVE ground system:
"DIST" (-) terminal on coil goes to distributor.
"BAT" (+) terminal on coil goes to key switch.

On a POSITIVE ground system:
"DIST" (-) terminal on coil goes to key switch.
"BAT" (+) terminal on coil goes to distributor.

doublebass73 · Jan 15, 2019

(quoted from post at 19:54:49 01/14/19)

(quoted from post at 16:18:36 12/10/18) Yes, you're right about current through the loads being opposite when you switch the grounds. That's a good diagram, hopefully that makes sense to the OP.

I did a quick search and found a few sources for 12V positive ground alternators so there's a good chance the OP has one. Here's one place that does them - http://www.qualitypowerauto.com/item_135/Positive-Ground-12-Volt-Alternator.htm

Click to expand...

ctually, current direction did not change because of where the circuit was grounded (positive or negative), but rather because of how you installed the battery. The same, I say, applies whether any part of the circuit was grounded or whether the circuit is totally isolated from ground. Word usage is everything!

So is context, if you read my original post to this thread you'd see that I agree with you. Here it is:

[b:c0b20b2905]"There is nothing wrong with positive ground. A ground is nothing but a common connection, it's still DC and electrons still flow in the same direction regardless of the ground connection to the battery. If the alternator is wired positive ground I wouldn't hesitate to run it that way. It's a good idea to have it tested first though."[/b:c0b20b2905]

JMOR · Jan 15, 2019

(quoted from post at 09:27:12 01/15/19)

(quoted from post at 19:54:49 01/14/19)

(quoted from post at 16:18:36 12/10/18) Yes, you're right about current through the loads being opposite when you switch the grounds. That's a good diagram, hopefully that makes sense to the OP.

I did a quick search and found a few sources for 12V positive ground alternators so there's a good chance the OP has one. Here's one place that does them - http://www.qualitypowerauto.com/item_135/Positive-Ground-12-Volt-Alternator.htm

Click to expand...

ctually, current direction did not change because of where the circuit was grounded (positive or negative), but rather because of how you installed the battery. The same, I say, applies whether any part of the circuit was grounded or whether the circuit is totally isolated from ground. Word usage is everything!

Click to expand...

So is context, if you read my original post to this thread you'd see that I agree with you. Here it is:

[b:f26487855d]"There is nothing wrong with positive ground. A ground is nothing but a common connection, it's still DC and electrons still flow in the same direction regardless of the ground connection to the battery. If the alternator is wired positive ground I wouldn't hesitate to run it that way. It's a good idea to have it tested first though."[/b:f26487855d]

greed, your 'original' was just fine.

12 volt Positive ground?

New User

Well-known Member

Well-known Member

Well-known Member

New User

Well-known Member

Member

Well-known Member

Well-known Member

Member

Well-known Member

Member

Well-known Member

Member

New User

Well-known Member

Well-known Member

Member

Member

Well-known Member

Similar threads