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Old 06-04-2008, 08:25 PM
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Hey guys, can someone explain me why should I polarize a generator? I have seen some articles explaining how to do it but what if I don`t? I`m working with early Ford V8s and I really like to know.


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Old 06-04-2008, 08:34 PM
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Click on this and read about it. http://www.starautoelectric.com/Technical.htm
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Old 06-04-2008, 10:55 PM
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When you polarize a generator you are really re magnetizing the armature. Generators tended to lose this magnetism during rebuild. If you hit an armature on the end when you remove the pulley ,you can sometimes lose this magnetism also. striking the end realigns the electrons in the metal and they will not charge until polarized again.
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Old 06-05-2008, 08:35 AM
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Originally Posted by south65ss
Hey guys, can someone explain me why should I polarize a generator? I have seen some articles explaining how to do it but what if I don`t? I`m working with early Ford V8s and I really like to know.

The article that Henry Highrise linked to will tell you WHY you need to polarize. As to the HOW; the article states that you need to "flash" the B terminal to the D terminal. I don't know what the D terminal is as I've not seen that designation on a regulator. I have always flashed from the B (battery) terminal to the A (armature) terminal. This should be done any time the wires have been disconnected and then reconnected to the generator and / or the regulator.

Here's what could happen if you don't.

Long story but some may find the lesson learned familiar.

Almost 50 years ago (really it was 1960) I had a stock '36 Ford 3 window Coupe. I was driving from Reno, Nevada to the San Francisco bay area at night. Just outside of Sacramento the lights got dimmer and dimmer and the engine began to miss. The amp gauge showed a negative charge. Turning the lights off allowed the current drain on the battery to be much less and the engine ran OK this way. I tailgated a tractor trailer so that I could see until I reached Vallejo. I got off the freeway there at a service station that was open all night. It seems that the cutout relay (pre voltage regulator) had burned up as well as the generator. I got the battery charged and drove with no lights (to save the battery) the rest of the way to my folks home in San Mateo. I went to Sears & Roebucks the next day. They didn't have a generator for a '36 Ford, nor did they have a cutout relay. What they did have was a rebuilt generator and voltage regulator for a '48 Ford which was a bolt on application. I installed the generator and found a spot on the firewall to mount the regulator. I wired it up. Simple. Hot wire to 'B' (Battery) terminal of the regulator. One wire from the 'A' (armature) terminal of the regulator to the 'A' terminal on the generator. Another wire from the 'F' (field) terminal on the regulator to the 'F' terminal on the generator. I even added a short wire from the mounting flange of the regulator to a good ground on the firewall to insure proper grounding. I read the instructions for installation. Saw that it mentioned about polarizing the generator BEFORE turning on the ignition switch. It even told how to do that. Being young and dumb I figured that was an unnecessary step and did not do that. Turned the ignition on and fired up the engine. AMP gauge went to max and then went to negative charge. Regulator began to smoke. Shut off the engine. Regulator was ticking very loud like a clock. Bummer! Re read the instructions. Seems that I really should have polarized the unit first. Removed the generator and regulator and returned them to Sears for exchange telling them that the unit didn't work. Installed the new generator and regulator. Polarized the unit three times. Fired it up. All was good. Lesson learned.

I left that car there and had my Dad sell it. I didn't trust my "fix" to make it back home. (Hey, I said I was young and dumb at the time) Took the Greyhound back to Reno.

Side note: I had another '36 Ford 3 window that broke down (overheated due to a cracked block) at the same service station the following year. I'll write about that adventure and how I solved it with "Water Glass" at another time.

Last edited by Frisco; 06-05-2008 at 08:50 AM.
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