The Stovebolt Site Forums The Shop Area The Electrical Bay Polarizing generator

Hey folks, curious if when disconnecting battery briefly on my 6 volt '54 3100 should I have to polarize or is there residual magnetism in the generator? Thanks in advance!

You should have pleanty of residual.

ChevyNoob Look here in the online Shop Manual under Generator- Installation for polarizing generator instructions...

Here is the Table of Contents page of the Shop Manual...

Hey thanks! So there would be no harm done to do this if the generator didn't need to be polarized?

I rebuilt mine with new brushes, bearings and springs... Had it all apart and when I put it in it worked fine not polarized... I later did polarize it just to make sure there was not going to be an issue...

It never hurts to go through the polarizing procedure - and, it it a simple procedure.

Soft iron such as the pole shoes for field coils do not retain magnetism very well. Polarizing creates a magnetic field by running current through the field coils, and some of it remains as "residual magnetism" after current stops flowing. Simply jumper battery voltage fron the "Bat" terminal of the regulator to the "Arm" terminal with the wires connected between the generator and the regulator for half a second or so, and the generator is polarized. Some guys short across the terminals with a screwdriver blade, but I prefer a short jumper wire. The most common way polarization is lost is if the generator housing is bumped or handled roughly during installation. A quick way to check for residual magnetism is to spin the generator with the wiring disconnected by running the engine. A polarized generator will develop about 1/2 volt or slightly more at the Armature terminal with no wires connected to it. Grounding the field terminal with the armature turning will cause a very high spike of voltage, up to 40 or 50 volts sometimes.
Jerry

Right on thanks fellas

Hello all,

I've just installed a new voltage regulator and battery, and had the generator rebuilt on my '61 Apache with 235-I6. I've got the infamous spinning generator going on, and I haven't polarized the regulator yet. My question is: Is it safe to polarize the regulator while the generator is spinning? If not, how best to proceed? Thanks in advance.

Greenman.

the generator is in the truck with the fan belt on? how is it 'spinning'? did it start spinning without the engine running? you should have polarized it as soon as it was installed, before the truck is ever started .... after you convince the generator to stop spinning, quickly short between the battery [b or bat] and generator [g or gen] terminals on the regulator

Bill

Hey Bill,

The truck has not yet been started. It does not yet have its fan belt installed. The generator started spinning as soon as I connected the battery. I've read a ton of posts where many people have experienced this and the fix is always to polarize. Since I know I haven't polarized my voltage regulator yet, I assume that's the issue, but I'm trying to find out if it's safe to do the polarization while the generator is spinning. I don't want to ruin a newly-rebuilt generator! Thanks.

Greenman.

for starters, it's the generator that gets polarized, although the standard way to do that is using the regulator terminals .... polarizing has to do with insuring the polarity of the voltage being generated is correct .... a generator motoring means the cutout relay in the regulator is closed and the generator is drawing current because it's directly connected to the battery when it shouldn't be - might mean the relay is stuck - review the manual section linked above

to start [assuming you disconnected the battery], put the fan belt on so the generator can't turn, reconnect the electrical circuits, polarize the system

Bill

Got the polarizing procedure down, but here comes a rookie question - do you do the procedure with the engine running, or not? Thanks.

not running, done as soon as everything is in place and hooked up

Bill

Thanks Bill. One more question: I looked at my generator & the two wiring posts are not labeled. One post has a rather thin wire & the other has a larger wire. Would the "ARM" post be the larger wire?

yes the armature wire is the heaviest, which would go to the regulator - the regulator should be labeled, short the batt[B] and gen[G] terminals momentarily

Bill