The Ford Barn - Polarize Generator

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- Model A (1928-31) (https://www.fordbarn.com/forum/forumdisplay.php?f=3)

- - Polarize Generator (https://www.fordbarn.com/forum/showthread.php?t=15272)

Polarize Generator

How do repolarize a generator?

Re: Polarize Generator

With the generator in the car and wired (but not running), take a short jumper wire and touch it across the in and out terminals of the cutout for 1/2 second two or three times. Expect a small spark. If the generator is out of the car, connect the genny frame to the battery terminal that is ground (+ on 6V, - if you are 12V). Touch a jumper from the other battery terminal to the genny output that goes to the cutout. You do not need the cutout in place to do this. If you are switching a genny that has been used on one polarity to the other (changing from + ground to -), you may have to zap it for a second a half-dozen times or so. What you are doing is using the field coil to magnetize the iron coil cores and frame, and if they have previously been set in the wrong direction you will be de-magnetizing them and remagnetizing in the new direction.

Re: Polarize Generator

If you have a modern cutout or voltage regulator that uses a diode you had better check with the manufacturer first (or wait to someone posts what to do).

Charlie Stephens

Re: Polarize Generator

ozkiwi ..............................
I was talking to a man, who owns a very successful generator and alternator shop, in Daytona Beach, Florida, about polarizing the generator in my 1934 FORD.
He said, "There is nothing to polarize on a generator, unless you are running a voltage regulator".
Is this true ? He sure knows his business !
I have always tried to polarize mine........
This is very curious,to me.
MIKE :confused:

Re: Polarize Generator

Quote:

Originally Posted by Charlie Stephens (Post 84219)

If you have a modern cutout or voltage regulator that uses a diode you had better check with the manufacturer first (or wait to someone posts what to do).

Charlie Stephens

If you have a diode instead of the cutout, jumping across it will do no damage. What you do not want to ever do with a diode is ground the output while the generator is running. That will overload it. The "Fun Projects" regulators, which require use of the 3rd brush and must be set to limit output to 15 amps, have a design that lacks spike protection and may suffer damage. If you have one of those, remove it, and then touch the generator output to a jumper from the cable connection on the starter switch.

Re: Polarize Generator

Quote:

Originally Posted by FL&WVMIKE (Post 84224)

. . .He said, "There is nothing to polarize on a generator, unless you are running a voltage regulator".

Bolderdash. I repaired many types of gennys and load tested them on a Sun generator test bench. Most generators have identical field pole iron cores. If you flip them on reassembly the generator will need to be flashed, or polarized. If you take apart a pile of identical gennys and reassemble from your parts stock, you may have two poles polarized north, or two south. The case may have a conflicting residual magnetism. The new owner may want to use it on a different polarity. Plenty of things may require flashing or polarizing it. I always DE magnetized cases, field pole cores, armatures, bearings, endplates. They were assembled that way and then flashed (polarized) just prior to load testing. There is no need to re-flash a fresh rebuild that has been bench load tested on the polarity you intend to use, but it is entirely possible for a fresh D.I.Y. rebuild or any gen that has sat for years to need polarizing. You'll know right away when you start and run it. If the cutout relay doesn't close it's either demagnetized or reversed.

Re: Polarize Generator

Quote:

Originally Posted by MikeK (Post 84259)

Bolderdash.

OK is that the nice word for BULL CRAP!!! hahahah Good one Mike!:)

Re: Polarize Generator

Quote:

Originally Posted by MikeK (Post 84248)

I had bought one of the Fun Projects EVR's for my model T and installed it on the car and followed the instructions for installation and setting the third brush as per the instruction sheet. When I turned off the headlights (following the instructions) the amps went up, and then all of a sudden nothing. The regulator was "damaged", which Fun Projects would be happy to fix for $20. I had the regulator "fixed" but I also bought a new diode-style 20 amp continous duty cut-out from one of the parts vendors. I installed that instead of the EVR from Fun Projects, no problems or damage to any component of the electrical system, as was predicted by those that had "fixed" the first EVR, and that was almost 10,000 mile ago.

When I had asked the folks (at Fun Projects) about one of the Fun Projects EVR's for my powerhouse generator (this was before I had gotten the EVR for the model T), I was told that it might not work well on the powerhouse generator. I was told that it (the powerhouse) may produce too much power for the EVR, and lead to damage. Either way I have stuck with the original style cut-out on the powerhouse but would one day like to upgrade/try the voltage regulator that Tom makes.