Electrical Help--6v. NEGATIVE Ground

Hugh in NC

Hugh in NC

Member
I just discovered today that my new to me 1930 ccpu has the 6 volt battery with the pos. going to the starter and the neg. going to ground. Everything works, the ammeter shows a positive charge when running. Should I just leave it alone? Or, should I change back to pos. ground? If I should change back to pos. ground, what if anything needs to be done? Your suggestions are welcome.

Thanks,
Hugh
 
I would change it back to make it less confusing for anyone trying to help you during an electrical problem. You'll need to switch the battery posts, and switch the ammeter posts. The two coil primary posts may need to be switched to have correct coil polarity. Repolarize the generator right after switching the battery posts to + ground. Polarize by jumping a short wire across the 2 cutout terminals.

If someone installed a diode cutout that will need to be changed also.
 
For many years, my A was set up with 6V negative ground. It makes no difference in performance as long as everything else is set up to match. As far as it confusing would-be helpers goes, it cuts both ways: Model A guys will be thrown off by negative ground; the other 99.9% of the mechanics in the world will be thrown off by positive ground. So, either way, it is wise to remind your helper how you are grounded.
 
If you get a short circuit, then immediately reverse the battery polarity, will the wires then suck the smoke back in? Probably not, (someone should tell Lucas) so make sure there is nothing electronic that was added to the vehicle.
 
If it ain't broke, don't fix it unless you want to. I would just leave it alone. Uncle Ray and I rigged up a six volt generator that came off a 1950 De Soto on my first model A. We wired it negative ground. I ran it that way with good results. That was long ago, its now running a stock 6 volt generator with cut out and wired positive ground.
 
There is nothing wrong with leaving it alone. BUT, you should check the wires feeding the coil to make sure that they are also setup for negative ground.

If the coil posts have (-) and (+) next to them, make sure the wire connected to the (-) finds its way to the points inside the distributor. If you have the original pop-out ignition switch, that wire will feed down to the points through this switch.

If you have an aftermarket ignition switch (simple on/off key switch) then it probably turns power to the coil on and off, and that wire should connect to the (+) post. The wire coming off of the (-) post would flow directly to the distributor points.

Your previous owner might not have known to switch the coil wires when they switched the polarity of the battery.
 
I would swap it back. Swap the battery, ampmeter, coil connections and your done.

Assuming you have a generator.
 
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What do, you have on it Making Electrical Current? A Original Generator or did some one install a Alternator?
I would't go changing around cables if You have a Neg Ground Alternator!
 
Mike V. Florida said:
It was funny until you tried to explain it:p
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Yep! when the purveyor of "humor" laughs at his feeble attempts, OR has to explain it,-----it's GONE.
You gotta' keep a "pickle puss" expression as if you're wondering, "WHY are they laughing"???? My problem is that when some look at me, they start laughin' 'afore I've even said ANYTHING???? Bill W.
 
It would be a good move to wrap red tape on the +ve cable, possably at starter and battery to aviod an error and of course saftey

My 'A' has the earth identified
 
Thanks for all of the advice. I will leave it alone for now. I will check the coil wires for polarity. Truck still has original generator and cutout.

Hugh
 
30Ford said:
wouldn't the starter run backwards with reversed polarity
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No. Since both the field and armature are wound electromagnets, both reverse, so it runs the same way. To reverse, flip the wires on either the field or armature, not both. A permanent magnet motor will reverse with a polarity change because you are not reversing the permanent magnet field.
 
MikeK said:
Didn't know dogs could laugh. That's what I like about the 'Barn. Ya learn something new every day.
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I need to learn 3 new things everyday, Mike, 'cause I likely have forgotten 2 things from my past miscellaneous file!
Re: Dog:cool: laughin' "A Dog's:cool: eyes have the power to speak a GREAT LANGUAGE! (Copied from my Dog:cool: calendar.) Gotta' get me a Dog:cool: clock that "WOOFS" each hour. Bill W.
 
BILL WILLIAMSON said:
I need to learn 3 new things everyday, Mike, 'cause I likely have forgotten 2 things from my past miscellaneous file!
Re: Dog:cool: laughin' "A Dog's:cool: eyes have the power to speak a GREAT LANGUAGE! (Copied from my Dog:cool: calendar.) Gotta' get me a Dog:cool: clock that "WOOFS" each hour. Bill W.
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2730897-T600450.jpg

Here is my little hound dog , Peppermint Patti. She is smileing here. I can look at her face and tell if she is happy. You just have to be in tune with them. I've got a dog clock that wags its tail each time it ticks.
 
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Hugh, See the link below for a device to check coil polarity. You may already have one of these. If not, it could be handy.

I'd swap the 6V polarity back to stock. My first thought was the same as Tom's. Model A'ers are used to positive ground. If you ever need electrical assistance alongside the road, that will be their first assumption. They won't likely say, "Hummm, I wonder if this is a negative ground system?"

My second thought was having the satisfaction of knowing that this small aspect of your car is stock. Sure, nobody will know or care that the electrons are going in the "wrong direction." But you'll know. Attending to these little details can be a source of pride and satisfaction even if nobody else sees. But that really depends on what you get out of the hobby. It's a personal choice and worth consideration.

http://parts.modelastore.com/show_Product.asp?ID=4181
 
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