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This has probably been covered before but I couldn't find it. I just installed a used generator and my ampmeter is centered when idleing but on increase in rpms it shows discharge. Do I need to polarize the generator?

Yes.

Thanks Cletis

Yes, take a short jumper lead and make a momentary connection between the BAT and ARM terminals of the regulator (about 1/2 second, just a quick flash. Running or stopped, it doesn't really make any difference. If you've got the top off the regulator, the set of points behind the BAT connection should close anytime the engine is started, and spring back open when it stops. Connecting the FLD terminal to ground with a jumper should send the generator into full output, but don't rev the engine much above a fast idle with the field grounded. The voltage can go WAAAAY too high if you do. Normal regulated voltage at the battery terminals against a fully charged battery will be around 7.5 volts on a 6V system, or 14.5 on a 12V system.
Jerry

Thanks, Jerry
I touched the "BAT" and "ARM" terminals but the ampmeter still shows discharge above idle.

does it show 'charge' immediately after you start? might just need to reverse the wires on the ammeter terminals

Bill

What is the voltage reading at the battery posts while the ammeter is showing "discharge"? Without measurements, all this discussion just turns into a SWAG.
Jerry

Here are some steps to take.
1. Check battery water and general battery condition to
see if it will take and hold a charge....Load testing
may be necessary.
2. Check wiring for damage and make sure all
connections at generator, regulator and battery are
tight and free of corrosion.
3. Make sure fan belt is tight enough to drive
generator at full capacity.
4. Run engine at medium speed. Using a wire, touch one
end to regulator base and other end to a good ground.
If this corrects trouble, regulator is not properly
grounded anymore.
5. If test 4 does not correct trouble, make this test.
Connect a wire from regulator terminal marked "ARM" or
"GEN" to regulator terminal marked "BAT" with engine
running at medium speed. If charging rate increases,
replace old regulator.
6. If test 5 does not correct trouble, make this test.
Connect a wire from "FLD" Terminal of regulator to a
good ground with engine running at medium speed. If
Charging rate increases, replace old regulator.

If none of the above test show a bad regulator then
there is probably a problem in the generator itself.

kennethw,
I went through all tests with little change in needle.
Before starting I get a battery reading of 12.5. With a medium idle I get a 12.8 reading at the battery and the ammeter shows discharge. Looks like I need to reverse the wires on the ammeter.
Ben

Is the cutout relay closing? If it is, the voltage regulator setting is too low. It needs to be at least 14 volts, and 14.5 or slightly above is better. 12.8 WILL NOT keep the battery up. Increase the spring tension slightly on the Voltage regulator points, the ones directly behind the Field terminal. Go easy- - - -a little adjustment goes a long way. The voltage will drop slightly after the cover is reinstalled, so adjust the voltage .1 or .2 volts higher than you want the final reading to be. Don't mess with the current regulator adjustment, and only raise the cutout relay closing voltage if the points do not spring open when the engine stops. The cutout relay should close as the armature voltage goes above 12.5 volts.
Jerry

Hotrod Lincoln,
Both sets of points appear to be touching whether the engine is running or shut off and they are not fused together. If I increase the spring tension won't that hold the points together?
Thanks for your help
Ben

P.S.
Hotrod lincoln,
I should clarify by touching I mean the points are away from the coils, touching the outer contacts.
thanks
Ben

Two sets of points will be spring-closed, the current regulator behind the Arm. terminal, and the voltage regulator points behind the Fld. terminal The cutout relay, behind the Bat. terminal will be held OPEN by a spring, and closes when the generator voltage goes higher than the battery. Increasing the spring tension of the VOLTAGE REGULATOR points makes the charge voltage go higher. That's the one behind the Fld. wire. Don't mess with the current regulator or the cutout relay right now, just increase the voltage a little.
Jerry

I don't know if this will help, but here's a copy of a circuit from a Delco-Remy service bulletin from the early 1950's. It shows the internal wiring of a typical 3-unit regulator.

http://www.hunt101.com/data/500/D-R_Regulator_001.jpg

Jerry

Hotrod Lincoln,
Thanks, Yes, the diagram of the regulator does help. My points on the current and voltage regulators are in the positions as shown in the diagram. Are they then in the charge mode? At no time ( starting, idleing, or fast idle) do they change. With the battery at rest I get a reading at the battery of 12.4. Should I bring the battery up to full charge first?

12.4 volts is a good reading for an "engine-off" measurement at the battery. A lead-acid cell that is fully charged has a specific gravity reading of the acid of 1.250-1.265, depending on the strength of the acid whan the battery was manufactured. A cell in that condition has an open-circuit voltage of 2.1 volts. A fully charged 6-cell battery ("12 volts") will have an open-circuit voltage of 12.6. Yours is close enough to that reading to be considered "full charged".

With the engine running, does the cutout relay close? From the voltage readings you've been quoting, I don't think it would be possible to get the relay closed. The closing voltage should be 12.5 at a minimum, to prevent the battery from discharging through the generator. If the cutout is closing, you definitely need to increase the spring tension on the voltage regulator points to increase the charging voltage.

You will not be able to see the current or voltage regulator points move. they're vibrating at a rate of several cycles per second, and the movement is measured in the thousandths of an inch. You might be able to feel the points vibrate by touching them gently with a fingertip. There's no shock hazard in doing that, BTW.
Jerry

Hotrod Lincoln,
with the engine running (after bending the field spring tab ever so slightly)I get a flash from the cutout relay then a constant flash on the current regulator points. Do I need to bend the field tab a little more?

Is the cutout relay staying closed? If the cutout is staying closed, what is the terminal voltage at the battery? Here's where you're beginning to need an accurate ammeter to tell you how much current is going into the battery. Try increasing the spring tension slightly on the current regulator points- - - -they should not be arcing excessively. The ideal setting will be 30-35 amps of current flow into the battery when the current regulator points are in control, and 14.7 volts against a fully-charged battery once the voltage regulator points take over. There should never be a situation where both voltage and current control points both operate at once- - - -it's an either/or situation.

It's a whole bunch simpler when I've got a student looking over my shoulder as I demonstrate regulator adjustments- - - -the internet leaves a lot to be desired!
Jerry

Hotrod Lincoln,
I've increased the spring tension on the current regulator points and that didn't make any difference.
When I increase the rpms to maybe 900 the cutout points close and the current regulator points begin arcing. When I let off of throttle and let the engine idle the cutout relay opens and the current regulator stops arcing and the ammeter returns from discharge to neutral.
Ben

OK, if the cutout is closing, you're developing voltage from the generator. The wires on the back of the ammeter need to be reversed to show "charge" when the cutout closes. You still haven't given me any voltage readings to work with when the cutout closes, so any advice I can give you about settings is a wild guess, particularly since there's apparently no way to measure amps. Unless the idle speed is VERY slow, the cutout shouldn't reopen at idle. Is the arc at the regulator points really severe, like a dead short, or just barely visible? it's possible your cutout relay is set way too high, but unless you can figure out some way to report on actual voltages while these things are happening, We're not going to make much progress.
Jerry

Hotrod Lincoln,
I have the idle speed at about 700 the book calls for 450 to 500, but unless my tach gage is wrong I don't think it will idle any slower. I can almost see the fan blades turning now. The arc at the regulator points is wery visible. I took a reading at the battery before starting and got 12.4. After startup and on increasing r's I got readings up to 16.6 then it seemed to settle on 13.5.
I'll reverse the wires on the ammeter.
Ben

Hotrod Lincoln,
P.S. I most likley have shorts. I'm just now digging into the wiring. I have a tail light hanging by the wire. I've lots of wiring to correct.
Also, thanks, so much for all your help.
Ben

OK, you're making progress! Sort out the obvious electrical gremlins and set the idle speed by ear- - - -I really doubt that your tachometer is giving you good information. Any idle speed around 500-700 RPM should be reasonable, and that should be adequate to keep the cutout relay points closed. The 16-ish number is a little high, but if it's just a spike that settles down quickly, don't get terribly concerned about it. Watch the liquid level in the battery- - -if you're getting a lot of gas bubbles or having to add water frequently, the voltage setting is too high.

Ideally, the dash-mounted ammeter should go 1/2 to 2/3 of the way toward "charge" immediately after startup, and gradually move back toward center as the battery recovers its charge. After running a few miles, about one or two needle's widths toward the + side is a good place to be. That's assuming you've got a battery that is in good condition. Have fun!
Jerry

Hotrod Lincoln,
Thank you, Thank you so much.
Ben