A guy at the NW meet had charing problems when he arrived.O'Rielly's got the generator rebuit and charged the battery.The car started but it was still discharging and went dead??They said it was a short futher down the line and told him to contact the tech,he left a a message and received no return call..Could this be as simple as polarizing?He is out $300.and is hoping to get back to Portland

If he took it off it has to be polarized to charge.

I would think if the generator was removed and reintalled at the meet site it would have been polarized after inatallation ?if it was done by the O'reily's Tech who knows,posibly not?

Why wonder if it was polarized or not?
Polarize it, charge the battery and see what it does!!
Are we sure we know that today's "techs" even know what the term "polarize" means?

Your right about that Ken!Whats said is I was having lunch with this poor guy yesterday and he was telling us his said tail..I never thought to go back to the hotel and polarize it for him.Whats even mre disheartening is that the guys health is bad and his wife was doing all the driving and the trip from the meet back home is probably 150 miles,the car I think is an early 40's..I hope they got it fixed and made it safely

I never heard of polarizing a generator! It was always the voltage regulator that needed polarized.

You can polarize the generator (eletrical system) at the generator or on a later car at the voltage regulator....its all the same.
To be honest I seldom do it and have never had a problem.

I always polarize a generator when it has been removed and reinstalled.

Yes "as stated in the shop manual"

The original question was...Will the generator charge if you rebuld it,reinstall and do not re-polarize?

Maybe......maybe not. It all depends upon the circumstances.

Some shops may have a generator test bench that has a positive ground system (mine does) so, in that case the generator would be polarized to a positive ground system. When the generator is installed on a negative ground system it won't charge unless the generator is repolarized.

I usually forget to do it, and have never had any problems, either...Knock on wood...

The shop manual also says if not polarized it may burn the regulators contacts?

That is true.

This being said Kevin find a BIG piece of wood to knock on..just kidding

I find a baseball bat a little handier...

I would say that it is best to follow the guidance in the maintenance manual. Last time I put on a generator, I had to polarize it.

It may have been the fact that i hooked the generator to a battery to see if it would turn. Upon installation it showed discharge. The manual told me to ground one of the terminal wires (Batt or Field?) at the voltage regulator. Did so and it started charging.

Charlie

Yep, that's why it is always recommened to re-polarize the generator upon installation each time after it has been removed from the car.

That is good to know, however I am the only Pseudo-Tech my cars ever know and I don't own a test bench. I just follow the instructions in the shop manual and likewise I always polorize. It only takes a few seconds before starting the car up after messing with the generator.

The gen on my '30 engine was showing discharge a few weeks back after a rebuild and I polarized it as suggested here using a jump wire across cutout. Worked fine after that.

Interestingly, I loosened the drive belt during a timing exercise and did not tighten it fully before starting car again. On the road I notice ammeter indicating discharge. When I got home I checked belt and realized how loose it was and so re-tightened it. I then repolarized the gen and charging working fine since.

Might not have to have re-polarized it, as the wiring had not been disconnected...Just tighten the belt...

My take on it is; it doesn't take long or hurt anything to polarize it, but the regulator could be damaged by not polarizing it if it needs it, so, if in doubt, polarize.

Just do it!!!!

To

Wow...I'd better remember to re-polarize, the next time I change the belt or water pump...

And, you need to polarize too when you change a tire or turn your radio on and off.

You forgot in mention when you disconnect the battery or change the oil....

Hi Guys sorry to interrupt, but how do you polarize a generator? I have a '27 Capitol, but haven't read anywhere about how to polarize!! I know mine could probably use it!! Thanks

MickyC,
Briefly touch a wire from the positive battery post to the output wire of the generator. In your case just jump around the cutout. Or disconnect the wire from the battery on the cutout and touch it to the wire coming out of the generator or that terminal on the cutout that the output wire screws onto.

OK, Thanks Chipper!

Hi there,
I have read with interest every post regarding "POLARIZING" a generator, yes every post, but not one mention of what "POLARIZING" is? or how to do it? and of course why it is needed?
can some learned gentleman on here explain my questions for all the other novice like myself?

BTW, is it needed if you drive at the north or south pole?

regards
Peter

There have been numerous posts here in the past on the procedure for polarizing a generator, both with a cut-out and with a voltage regulator. You might want to do a search on Chevy Chatter for the previous posts describing how to polarize a generator.

For additional information go to this web site:

http://web.utk.edu/~tprather/FoothillsTractorClub/TechTips/PolarizeGenerator.html

Go back and read the previous page. I don't have the answer for all your questions, however polarizing I believe refers to the magnetic field and setting the direction in which the current will flow. Direct current flows from positive to negative so if the input of the generator is positive there will be no current output. Think of it as magnets where one side attracts and the other repels. Polarizing the generator changes the magnetic direction of the fields. If I have messed up what I have posted I am sure it will get corrected.

The generator voltage is induced in the generator armature rotating in the magnetic field from the poles fixed inside the generator casing. The poles are magnetised (excited) from the generator itself when generator voltage causes current to flow in the pole (field) windings. At standstill the generator voltage, of course, is zero. The generator voltage build-up after starting the engine is initiated by the small remaining magnetism in the poles from last time the generator was running. Normally this remanence will always be present, but it can be lost if the generator has been disassembled or the vehicle has been out of use for a long period. (Or if voltage of opposite polarity have been applied, poles have been interchanged, etc.) If remanence magnetism is lost, voltage will not build up when armature rotates. Cure is, as explained in previous postings, to apply current from the battery to the generator by bypassing the cut-out relay with a piece of wire for a short moment. If this does not work, check wiring and field winding continuity.

Polarizing is to reestablish the remanence (residual magnetism) of the generator poles.

A fairly good description is given in Chevrolet Repair Manual for the International and Universal Models, a 272 pages booklet available in reprint copies.

Good luck,

Einar

hi there Einar,
thank you for posting your clear reply, I now understand the meaning and what to do if needed, thank you very much from down under....
Peter

Hi there,
I now have to polarize my generator.
Do I do it with the ignition ON or OFF.?

Peter

Off.

I think that I would have said
OFF!!!

Okay......... OFF!!!!!!

Really...?

Really...
It's raining here in California and I got nothing better to do... Sorry

You obviously have way too much time on your hands......

thanks for the advice, BUT, are you absolutely sure about that, I mean really , truly , absolutely sure that it has to be OFF?

as in standing on your head Sure?

its not raining in New South Wales today either.....

Peter

OFF!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Great topic. I really learned something. My thanks to all.

Cool! Glad that we were able to help you out.

Glad you did too, but do you think we went OFF subject a wee bit?

Nope!!