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08-05-2015, 12:13 AM | #1 |
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Location: Tamborine Mountain,Queensland, Australia
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Incorrect battery polarity issue.
I recently purchased a 1928 Pheaton that has been extensively rebuild, looks wonderful. Earlier today I was replacing the instrument panel light when I realized that the polarity is incorrect. The earth is Negative. I should mention all the electrical components are working eg. starter, charging system (generator), lights horn etc.
My question is this. If I change the battery cables to their correct battery (6 volt)terminals, ensuring a Positive earth, what systems would be effected? My main concern is the ignition and charging systems. Any advise would be most welcome. |
08-05-2015, 01:14 AM | #2 |
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Re: Incorrect battery polarity issue.
The coil wires have to be switched, the amp meter wires switched, and I think the generator has to be re polarized. You get more info tomorrow, I'm sure.
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08-05-2015, 07:41 AM | #3 |
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Re: Incorrect battery polarity issue.
Could the best solution to be to leave the car as you bought it ?
Switching to a negative ground system was a chance that was recommended if you installed a radio in your Model A so it was not uncommon to have a Model A with a negative ground system. Note : Information I have read does say that the generator works "better" with a positive ground system. Marc |
08-05-2015, 09:27 AM | #4 |
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Re: Incorrect battery polarity issue.
I would change to the positive ground because that's the way it was made and what everyone would expect to find if they offer help for a problem. Just switch the battery around, then jump the 2 cutout terminal for one half second to polarize the generator. Now turn on the lights with the engine off and see if the ammeter reads discharge. If it reads charge, then switch the wires on the back of the meter.
Also check the coil polarity to see if it's correct. If it's not correct just change the wires on the primary terminals around. The chicagolandmgclub has an excellent short description on checking coil polarity. Do a google search for "coil polarity" and you'll find it's the first or second listing. |
08-05-2015, 10:42 AM | #5 |
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Re: Incorrect battery polarity issue.
Chiefs' family cars' ammeter was hooked backwards, he just left it that way for LAFFFS! Once he used it as an "excuse", NOT to have to take a Guy to town, "LOOK, my generator AIN'T working"!
Bill W.
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08-05-2015, 10:46 AM | #6 |
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Re: Incorrect battery polarity issue.
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08-05-2015, 11:20 AM | #7 |
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Re: Incorrect battery polarity issue.
The battery was in backwards on my roadster. It ran fine, but when I installed LED tail lights, they would not work. Eventually I figured out the battery was in backwards. I turned it around, repolarized the generator and was good to go.
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08-05-2015, 01:02 PM | #8 | |
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Re: Incorrect battery polarity issue.
Quote:
That does it!
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08-05-2015, 03:50 PM | #9 |
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Location: Tamborine Mountain,Queensland, Australia
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Re: Incorrect battery polarity issue.
Thanks to all your comments and advise. I will give it a go today and post the (I hope) "positive" result.
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08-05-2015, 07:54 PM | #10 |
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Re: Incorrect battery polarity issue.
You do have a generator and not an alternator....Correct?
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08-05-2015, 11:00 PM | #11 |
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Location: Tamborine Mountain,Queensland, Australia
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Re: Incorrect battery polarity issue.
That is correct Russell, generator is installed.
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08-06-2015, 04:28 AM | #12 |
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Re: Incorrect battery polarity issue.
How come no one asked for a picture? Which tourer you buy? What part of Qld you in?
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08-06-2015, 03:53 PM | #13 |
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Location: Tamborine Mountain,Queensland, Australia
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Re: Incorrect battery polarity issue.
Hi Manager, we live on Tamborine Mountain and the vehicle is a 1928 Pheaton as mentioned on my first post. See attached.
Updating on the battery polarity issue. Thanks to the post replies, I have been able to get it all sorted. The generator worked without re polarizing it, the coil terminals were checked using a pencil and the amp meter wires were switched to indicate a charge. Last edited by chrisabes; 08-06-2015 at 03:54 PM. Reason: Additional wording |
08-16-2015, 09:22 PM | #14 |
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Re: Incorrect battery polarity issue.
The1929 Fordor I recently purchased was also converted to negative ground at some point. I would like to go back to positive ground. This may sound dumb, but don't DC motors turn in the opposite direction if the leads are switched?
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08-16-2015, 09:48 PM | #15 |
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Re: Incorrect battery polarity issue.
Coneross-A
The model a starter is a series type DC motor. What this means is that the field winding is in series with the armature. So, the motor turns the same way for positive and negative ground cars. The series type of motor was used because it develops a large amount of torque when it isn't turning. As the speed increases, the amount of torque drops. Thus, it has the high torque when it needs it..to start the car. For a shunt fed motor, the direction would change if the leads where changed in polarity. Also, the torque isn't as large when it isn't turning. So the shunt fed motor isn't ideal as a starting motor. Ford used the series fed motor because it is the best as a starter for the engine, not because it could be used for positive or negative ground electrical systems...that's just an extra benefit. Marc |
08-16-2015, 09:52 PM | #16 | |
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Re: Incorrect battery polarity issue.
Quote:
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What's right about America is that although we have a mess of problems, we have great capacity - intellect and resources - to do some thing about them. - Henry Ford II |
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08-16-2015, 10:02 PM | #17 |
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Re: Incorrect battery polarity issue.
pretty looking car, Governor....
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08-23-2015, 08:41 AM | #18 |
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Re: Incorrect battery polarity issue.
Marc,
Thanks for the explanation of the starter motor characteristics. |
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