The Ford Barn

Colonel · 03-13-2011, 09:36 AM

Model A's have positive terminal battery ground. I have one that has a negative ground setup. I don't know why the ground is set up for the negative battery terminal and would be interested in anyones thoughts. I also want to know if I can just redo the cables the right way-- ground the positive and hook the negative to the starter. If I do will that cause any other problems? Is there anything else I would need to do to make sure things are right? All feedback appreciated.

RonC · 03-13-2011, 09:42 AM

Switch the cables. Two things to look for after you start the car. see which way the ammeter needle moves. If it moves backwards reverse the wires at the bAck of the ammeter. If you have no charging from your Generator than you have to polerize it. It depends on your cutout type for the method of polarization.

Also check your coil wiring. If it is wired backwards your engine performance will be affected. You can check it by making sure the plus side goes to the points. If your coil is unmarked then use a number 2 pencil to determine the polarity.

Read this for the pencil test. The spark should be between the plug and the wire regardless of the ground setup.
http://books.google.com/books?id=viU...page&q&f=false

Patrick L. · 03-13-2011, 10:38 AM

Are you using an original type generator or alternator ???

Tom Wesenberg · 03-13-2011, 10:47 AM

It would be my guess that the owner may not have known Model A's are positive ground, so he did what most modern cars do and used the negative post for ground. Ron pretty well covered it, and to polarized the generator just jump a wire across the two cutout terminals for 1 second and you are done.

As Pat mentioned, if someone set it up for negative ground using an alternator, then you are stuck with it unless you change to a positive ground alternator, or better yet switch back to the original generator and install an electronic voltage regulator to get the benefits of a regulated charging system.

Jordan · 03-13-2011, 06:38 PM

There is no negative affects to running a negative ground 6 volt system. I would just leave it the way it is.

JC60B · 03-13-2011, 09:45 PM

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Except maybe weak spark from the coil. Works that way with 12v systems.

James Rogers · 03-14-2011, 06:25 AM

Quote:

Originally Posted by Jordan

There is no negative affects to running a negative ground 6 volt system. I would just leave it the way it is.

Unless the generator is original stock. In this instance the generator will discharge the battery and reverse charge it causing a volatile condition and destroying the battery. Reverse charging the battery creates an excess of hydrogen gas and a spark, like removing a battery cable, can cause an explosion. It would need to sit for a while before doing the work to let this gas dissipate.

RonC · 03-14-2011, 07:47 AM

There is no negative effect to running a stock Model A electrical system negative ground. In fact Ford ran Model T's with the same charging system as "negative" ground. I believe Ford thought running a positive ground would be a better system at the time so they switched for the Model A. A stock Model A generator does not care if it's negative or positive ground. It will not flow electricity in reverse or discharge your battery if you switch the ground. It will just not charge until re-polarized or flashed to realign the magnet poles.

billwill · 03-14-2011, 08:33 AM

Quote:

Originally Posted by Colonel

Model A's have positive terminal battery ground. I have one that has a negative ground setup. I don't know why the ground is set up for the negative battery terminal and would be interested in anyones thoughts. I also want to know if I can just redo the cables the right way-- ground the positive and hook the negative to the starter. If I do will that cause any other problems? Is there anything else I would need to do to make sure things are right? All feedback appreciated.

the charging system shouldnt charge the battery the why it is hooked up.

03-13-2011, 09:36 AM	#1
Colonel Senior Member Join Date: Nov 2010 Location: Indiana Posts: 251	6v Battery Negative Terminal Ground? Model A's have positive terminal battery ground. I have one that has a negative ground setup. I don't know why the ground is set up for the negative battery terminal and would be interested in anyones thoughts. I also want to know if I can just redo the cables the right way-- ground the positive and hook the negative to the starter. If I do will that cause any other problems? Is there anything else I would need to do to make sure things are right? All feedback appreciated.

03-13-2011, 09:42 AM	#2
RonC Senior Member Join Date: May 2010 Location: Rhode Island Posts: 1,868	Re: 6v Battery Negative Terminal Ground? Switch the cables. Two things to look for after you start the car. see which way the ammeter needle moves. If it moves backwards reverse the wires at the bAck of the ammeter. If you have no charging from your Generator than you have to polerize it. It depends on your cutout type for the method of polarization. Also check your coil wiring. If it is wired backwards your engine performance will be affected. You can check it by making sure the plus side goes to the points. If your coil is unmarked then use a number 2 pencil to determine the polarity. Read this for the pencil test. The spark should be between the plug and the wire regardless of the ground setup. http://books.google.com/books?id=viU...page&q&f=false Last edited by RonC; 03-13-2011 at 10:03 AM.

03-13-2011, 10:38 AM	#3
Patrick L. Senior Member Join Date: May 2010 Location: Largo Florida Posts: 7,225	Re: 6v Battery Negative Terminal Ground? Are you using an original type generator or alternator ???

03-13-2011, 10:47 AM	#4
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: 6v Battery Negative Terminal Ground? It would be my guess that the owner may not have known Model A's are positive ground, so he did what most modern cars do and used the negative post for ground. Ron pretty well covered it, and to polarized the generator just jump a wire across the two cutout terminals for 1 second and you are done. As Pat mentioned, if someone set it up for negative ground using an alternator, then you are stuck with it unless you change to a positive ground alternator, or better yet switch back to the original generator and install an electronic voltage regulator to get the benefits of a regulated charging system.

03-13-2011, 06:38 PM	#5
Jordan Senior Member Join Date: May 2010 Location: Ft. Worth Posts: 1,006	Re: 6v Battery Negative Terminal Ground? There is no negative affects to running a negative ground 6 volt system. I would just leave it the way it is.

03-13-2011, 09:45 PM	#6
JC60B Member Join Date: Mar 2011 Location: Edmonton Alberta Canada Posts: 85	Re: 6v Battery Negative Terminal Ground? Sponsored Links (Register now to hide all advertisements) Except maybe weak spark from the coil. Works that way with 12v systems.

03-14-2011, 07:47 AM	#8
RonC Senior Member Join Date: May 2010 Location: Rhode Island Posts: 1,868	Re: 6v Battery Negative Terminal Ground? There is no negative effect to running a stock Model A electrical system negative ground. In fact Ford ran Model T's with the same charging system as "negative" ground. I believe Ford thought running a positive ground would be a better system at the time so they switched for the Model A. A stock Model A generator does not care if it's negative or positive ground. It will not flow electricity in reverse or discharge your battery if you switch the ground. It will just not charge until re-polarized or flashed to realign the magnet poles. Last edited by RonC; 03-14-2011 at 07:56 AM.