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Old 08-27-2010, 07:16 PM   #1
cardoza
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Default Battery Polarity HELP

I purchase my 1928 a few years ago, but it is now when I realized that the battery is connected negative to ground (as you can see, I rarely used the car) and now I am retaking the hobby and I have to replace the battery. (6 volts)


The question: what will happen if I reverse the connection (positive to ground)?

I cannot find any markings on the starter motor or generator that will indicate that they are negative to ground.

Was there any model A in 1928 built with negative to ground?

Any procedure to follow, indication, hint, or help, will be appreciated..thanks
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Old 08-27-2010, 07:44 PM   #2
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Default Re: Battery Polarity HELP

No Model A Fords were built with Negative ground.
The Starter is not bothered by polarity. It will operate properly either way. Postive ground or negative ground.
Install the new battery with the Postive post attached to the chassis.
Polarize the generator using a small jumper wire momentarily connecting. to the rwo electrical connectionws on the cutout.
If the ammeter reads backwards wth the generator charging, reverese the wires on the ammeter.
I don't think I left anything out.
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Old 08-27-2010, 08:26 PM   #3
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Default Re: Battery Polarity HELP

Make sure you have a stock cut out. You may damage some of the modified systems
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Old 08-27-2010, 09:16 PM   #4
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Default Re: Battery Polarity HELP

All of what Mag said but if the coil is correctly wired for negative ground you will need to reverse the wires on the coil. It will run either way but it won't crank and run as well if the coil polarity is reversed.

Not to start a war here but if it was mine and it wasn't giving any problems with the negative ground hook up I would just put the new battery back the way the old one was. Otherwise your going to have to reverse four wires and polarize the generator. If you are running the can style regulator that is the negative ground type you will fry the regulator if you try jumping a wire across it to polarize. Also the negative ground regulator will not work on positive ground. So if you are now running a can style regulator you will have to buy a new one if you convert back to positive ground. Just a few thoughts to consider. Good luck.
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Old 08-27-2010, 09:56 PM   #5
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Default Re: Battery Polarity HELP

My 1930 Tudor was wired 6-volt negative by a previous owner and it has been no problem at all.

See previous thread:
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Old 08-30-2010, 07:58 PM   #6
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Default Re: Battery Polarity HELP

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Thanks guys for the advice, since the procedure to re-polarize the generator is new to me,
I will try to starting the motor, positive to ground, generator disconnected, to see if the cranking is better... then I'll work with the generator...will post results if any noticeable difference..thanks so much
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Old 08-30-2010, 11:37 PM   #7
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Default Re: Battery Polarity HELP

Quote:
Originally Posted by cardoza View Post
Thanks guys for the advice, since the procedure to re-polarize the generator is new to me,
I will try to starting the motor, positive to ground, generator disconnected, to see if the cranking is better... then I'll work with the generator...will post results if any noticeable difference..thanks so much
Changing the ground will not improve the cranking. You need to clean all grounds and make sure you are using battery cables (both of them) designed for 6 volts not some modern parts store cables designed for 12 volts.

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Old 08-30-2010, 11:56 PM   #8
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Default Re: Battery Polarity HELP

DO NOT RUN THE ENGINE WITH THE GENERATOR DISCONNECTED unless you ground the generator output terminal. A stock Model A generator not connected to the battery can put out about 40 volts and burn itself out.

Grounding the output stud keeps the generator output at zero.
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Old 08-31-2010, 08:49 AM   #9
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Default Re: Battery Polarity HELP

What about the horn when you change polarity? I don't know if it will run properly in either direction.
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Old 08-31-2010, 09:26 AM   #10
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Default Re: Battery Polarity HELP

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What about the horn when you change polarity? I don't know if it will run properly in either direction.
The horn is a motor like the starter. It doesn't care about polarity.

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Old 09-01-2010, 02:57 AM   #11
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Default Re: Battery Polarity HELP

Thanks for the input once more! here there are some results: with positive to ground,

The cranking of the motor felt different and the car started sooner (go figure), the cranking seems smooth and less noisy!!!

I did not ground the generator, however it was entirely disconnected and I hope it did not get damaged, because there is not excitation current going to it ..
I do have the can type regulator and will try to re-polarize for a quick test

(of course if the generator have magnets inside then I'll say it is fried)...
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Old 09-01-2010, 03:00 AM   #12
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Smile Re: Battery Polarity HELP

and... yes the horn worked with either polarity (I tried)...txs
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Last edited by cardoza; 09-01-2010 at 03:01 AM. Reason: verbs !!!
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Old 09-01-2010, 10:57 AM   #13
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Default Re: Battery Polarity HELP

Quote:
Originally Posted by cardoza View Post
Thanks for the input once more! here there are some results: with positive to ground,

The cranking of the motor felt different and the car started sooner (go figure), the cranking seems smooth and less noisy!!!

I did not ground the generator, however it was entirely disconnected and I hope it did not get damaged, because there is not excitation current going to it ..
I do have the can type regulator and will try to re-polarize for a quick test

(of course if the generator have magnets inside then I'll say it is fried)...
You are going to keep on until you ruin something, if you haven't allready. It is your car and I am not trying to be a smartazz. When the generator is turning above idle it will be putting out volts and amps. if the wire is disconnected and the generator is not grounded there is nowhere for the volts and amps to go and the generator will quickly self destruct. When you try to polarize the generator by jumping a wire across the can regulator you are going to ruin the regulator and I have twice warned. If you insist on changing back to positive ground you are going to have to buy a new positive ground regulator. The negative ground unit will not work on positive ground and will be destroyed by jumping across the posts. If it was giving no problems running negative ground it is just going to cost work and money to change it back. The starter knows NO difference in polarity and if it sounded different it was probably caused by poor cable connections, one way or the other. This is a classic example of if it ain't broke fix it untill is is.
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Old 09-01-2010, 11:11 AM   #14
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Default Re: Battery Polarity HELP

Maybe it started better because when the former owner switched to negative ground they didn't change the polarity of the coil. So when you switched to pos. groung the coil worked as intended. I think Purdy is giving you good advise; neg. ground won't hurt abit.

My A is in pieces, almost back together. It didn't have any wiring so I put all that in, had the generator checked because I had no idea. It checked fine except it was polarized neg ground. I had the Generator guy put it back to pos ground. I almost had the wiring done, was checking my turn signals and the only way to get the flasher to work right (the indicator bulb on the handle) was to hook it up neg ground. So I switched wires on my coil, re-flashed the gen and switched the amp gauge wires. I will be running neg ground.
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Old 09-01-2010, 12:26 PM   #15
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Default Re: Battery Polarity HELP

Quote:
Originally Posted by cardoza View Post
Thanks for the input once more! here there are some results: with positive to ground,

The cranking of the motor felt different and the car started sooner (go figure), the cranking seems smooth and less noisy!!!

I did not ground the generator, however it was entirely disconnected and I hope it did not get damaged, because there is not excitation current going to it ..
I do have the can type regulator and will try to re-polarize for a quick test

(of course if the generator have magnets inside then I'll say it is fried)...
I still stick with my opinion that the starter will work the same positive or negative ground. Assuming you didn't change the cables when you switched them then you "cleaned" the grounds when you removed and replaced the cables. Try switching back to negative ground and see how the starter sounds. As others have stated SEVERAL times do not run the generator without hooking up the wires. Remove the fan belt if you are testing (or course since the water pump is disconnected do not run the engine very long).

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Old 09-01-2010, 08:09 PM   #16
Tom Wesenberg
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Default Re: Battery Polarity HELP

Quote:
Originally Posted by cardoza View Post
Thanks for the input once more! here there are some results: with positive to ground,

The cranking of the motor felt different and the car started sooner (go figure), the cranking seems smooth and less noisy!!!

I did not ground the generator, however it was entirely disconnected and I hope it did not get damaged, because there is not excitation current going to it ..
I do have the can type regulator and will try to re-polarize for a quick test

(of course if the generator have magnets inside then I'll say it is fried)...
2 points to make:

1. You say you have the can type regulator. Are you calling the stock cutout a regulator, or do you know for a fact that you have a can type regulator made by John Regan?

2. You don't need to have the wire connected to excite the generator. The residual magnetism is what excites the generator and running it without being connected to the battery can make it put out up to 40 volts and it will fry itself if run for very long this way. I only run it this way for a few seconds to show people how many volts it can put out when disconnected from the battery.

Sometimes the generator can loose it residual magnetism if it has sat idle for a long period of time. Simply supply battery voltage to the output stud to remagnetize the generator. The easiest way to do this is to use a short wire to jump the 2 cutout terminals for 1 or 2 seconds.

If you have one of John Regan's can type regulators, he says DO NOT polarize by jumping across the 2 terminals. In that case, I'd remove the regulator and touch battery voltage to the generator output stud for 1 or 2 seconds, then reinstall the regulator. This way there would be no chance of burning out the regulator.
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Old 09-04-2010, 07:57 PM   #17
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Default Re: Battery Polarity HELP

Finally my car is positive to ground (I had to do it )

FINDINGS:
Tom W: I used the wrong name it is a cutout!!!
Purdy: you are right, high voltage generates when generator is not grounded my case 15 to 18 volts in a few seconds and ...
MAG the amp-meter reads backwards...

anyhow I used this link to learn more about what I have

http://www.ytmag.com/articles/artint4.htm

and I never knew about three brushes generators and settings for night driving!!

anyhow thanks so much for the sound advice and warnings the put me back in the learning process..
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Old 09-04-2010, 10:14 PM   #18
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Default Re: Battery Polarity HELP

Quote:
Originally Posted by Tom Wesenberg View Post
2 points to make:

1. You say you have the can type regulator. Are you calling the stock cutout a regulator, or do you know for a fact that you have a can type regulator made by John Regan?

2. You don't need to have the wire connected to excite the generator. The residual magnetism is what excites the generator and running it without being connected to the battery can make it put out up to 40 volts and it will fry itself if run for very long this way. I only run it this way for a few seconds to show people how many volts it can put out when disconnected from the battery.

Sometimes the generator can loose it residual magnetism if it has sat idle for a long period of time. Simply supply battery voltage to the output stud to remagnetize the generator. The easiest way to do this is to use a short wire to jump the 2 cutout terminals for 1 or 2 seconds.

If you have one of John Regan's can type regulators, he says DO NOT polarize by jumping across the 2 terminals. In that case, I'd remove the regulator and touch battery voltage to the generator output stud for 1 or 2 seconds, then reinstall the regulator. This way there would be no chance of burning out the regulator.
Tom, I know now that it turned out cardoza had a cut out. Just for the sake that anybody following this thread doesn't get the wrong impression, I would like to say this. The cut out will function the same positive or negative ground and you can polarize the generator by jumping across the terminals. I know that you mean well and please don't take this as me being a smartazz. There are two seperate versions of the 6 volt can regulator that John makes. One is made for positive ground and a different model is made for negative ground and they will not work vise versa. You also can't polarize across the posts of either.
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Old 09-05-2010, 07:07 AM   #19
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Default Re: Battery Polarity HELP

If you have a Nu-Rex Alternator, is there any problem in reversing polarity??

Mine is still positive ground, and except for a spell of dark nights because I grounded the headlamps back to the Negative terminal of the battery, it works just fine as is.
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Old 09-08-2010, 02:43 AM   #20
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Default Re: Battery Polarity HELP

I will say that if you get an alternator with a given polarity, one will not be able to change polarity due to the solid state hardware that comes inside it.. (...course I may be wrong..)
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Old 09-08-2010, 05:51 AM   #21
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Default Re: Battery Polarity HELP

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Originally Posted by cardoza View Post
I will say that if you get an alternator with a given polarity, one will not be able to change polarity due to the solid state hardware that comes inside it.. (...course I may be wrong..)
You are correct!
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