Yet another generator question

Wed Aug 18, 2004 8:09 pm

Here's what I've got...

'48 w/voltage regulator on top of generator. The machine is a converted battery ignition.

Light switch is a 4-selector

L term is connected to the center of the light switch.

Front and rear lights work fine.

Ammeter is wired as per diagrams.

Pull ignition switch out, slight reading on ammeter but hardly noticable.

Start engine. No charging evident on indicator.

Put switch to bright lights "B", shows about 9 amps but they don't appear to be discharging. Switch to Dim and the ammeter shows about 6 amps. Doesn't appear to discharge. (Maybe the gen is charging but ever so slightly)?

I've let "Henry" run for an hour with still no charge evident.

Have cleaned and tested grounds.

Have charged the battery off tractor and when I connect it, it shows 4, maybe 5 amps.

Here's what I need....

A new generator? New voltage regulator? Sanity check?

Wed Aug 18, 2004 8:24 pm

When you say it shows 9 amps and 6 amps, is that a positive deflection or negative?
If you don't have a cheap multimeter I'd suggest you pick one up from Harbor Freight or (dare I say it) Radio Shack and check battery voltage under these conditions.

A positive 6 to 9 amps charge would be acceptable.

Wed Aug 18, 2004 8:33 pm


Positive when the lights are on but, the ammeter never indicates its charging, just that when the lights are on, there's 6 amps on dim and 9 amps on bright. The funny thing though is that with the engine running, they never seem to discharge so this indicates something is charging. I have a multimeter and have tested the battery which shows a consistent 6 volts whether or not the engine is running. Shouldn't I see current on the ammeter with a battery ignition even if the engine is off and the ignition switch in the on position? And. When the engine kicks over, shouldn't I then see the charge indicator steadily creep up no matter where the lightswitch is positioned? And... Since I have the L terminal connected to the center of the light switch and don't have the field resistor coil in service any longer, I should be charging on high all the time correct?

I should mention that if I kill the engine and then start it up 3 or 4 times, the battery usually dies. Voltage then across the battery is about 4 volts.

I'll have to check but I think my multi-meter is from Sears. I would agree with you but need to add that Radioshack's pretty much only good for batteries and, while we're on the subject, overcharging the customer... :wink:

Wed Aug 18, 2004 8:35 pm

Bigdog wrote:
Radio Shack

:lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol:
The only real radio shack is the kind like Rudi's. I tend to stay out of the other places unless I need a battery or clip leads.

Wed Aug 18, 2004 8:37 pm

First, with the tractor not running, the ammeter should show a discharge when the lights are turned on. If it is showing positive, either the ammeter is connected backwards or you have the battery installed backwards. The 6 volt system should be positive terminal to ground. So, let's clear that question up first. Is the positive terminal on the battery connected to ground?

Wed Aug 18, 2004 8:55 pm

The positive terminal on the battery is connected to ground. Negative goes to my starter. Negative from ammeter also to starter and positive from ammeter to VR Batt terminal. F on VR terminal to F on Gen. L from VR to ignition switch and then from ignition switch a fuse is wired in series to one of the center posts on the light switch.

Now for your question... hold on and let me go to the shed...

Ok, that settles that. With engine off, ammeter read 9+ amps. After about 10 minutes it crept down to 8. I cranked the engine over and the needle dipped toward -. After 3 tries the battery died and now with the lights on, the ammeter reads about 4+ amps.

So, I guess this suggests a charging problem huh? Another thing too is that this probably rules out a problem with the battery since it is holding whatever charge is left on it from when I jump start correct?

Wed Aug 18, 2004 9:06 pm

Scotty, with the engine off the reading should be 9 amps DISCHARGE (left side of meter). If it's reading 9 amps charge, the meter is reversed, or the battery is charged backward (yes it can happen). When you used your meter what polarity were you reading? If it's an analog meter you would have needed the + lead on ground and the - lead on the battery terminal for it to read properly. If it is connected that way the ampmeter is reversed. The battery should read approx 6 1/4 volt at rest (not real critical), and 6 1/2 to 7 1/4 with engine running at mid to full throttle. Have you polarized the generator?

Wed Aug 18, 2004 9:20 pm

Yeah, what John said.

Wed Aug 18, 2004 9:26 pm

So the wife thinks I'm crazy. What are ya gonna do? It's 10:00 on the Eastern Coast and I'm out in a dark shed switching ammeter leads around and toying with a voltmeter.

Anyway. You guys were right. I'm now reading minus 8 amps with the brights on. When I fire up the engine (battery's just about dead), the ammeter bumps to + briefly but never gets past 0. When the engine kicks over, it does back to about -8.

Ummm volt readings on battery. Check. Positive lead is on ground side and negative lead is on load side. Battery before engine kicked over, 4 volts. Battery after engine kicked over. 4 volts.

Looks like I'm about to enter into the world of generator rebuilding huh?

Wed Aug 18, 2004 9:28 pm

Don't jump on that generator just yet. If the battery is bad (cell shorting out) it can load the generator.

Take the battery out and get it tested under load.

Wed Aug 18, 2004 9:35 pm

Ok, BigDog. That sounds like a pretty good plan to me. I'll try that and get back to you.

Wed Aug 18, 2004 10:52 pm

I know it's dificult with the hood on, but also take a voltmeter reading (engine running) at the generator, and at the battery side of the regulator/cut out, which ever you have. Just remembered you said it was on top of the generator, so you have a cut out and not a regulator. Try grounding the L lead that you hooked to the light switch. That is what controls your charge rate. Grounding it will put the generator at full charge. If that makes it charge clean the paint off where the light switch bolts to the dash. The 4 position light switch switch MUST have a ground for the charging circuit to work.

Thu Aug 19, 2004 5:06 pm


Well, the saga continues. As in my earlier post, the L from the cutout is wired to my ignition switch and then from there, there is a fuse in series to the center of the light switch. I tried grounding that L wire from the ignition switch and the ammeter dropped off the map to -20 discharge and the engine tries to cut out. I haven't yet tried the other tests that you suggested but this one concerned me.

Thu Aug 19, 2004 6:00 pm


I forgot to mention that I charged the battery up and had a load test on it at work. It tested fine. :(

Thu Aug 19, 2004 6:42 pm

If it has an L terminal, it's not a cut-out. Grounding the L will short circuit the system. Ground the F terminal not the L terminal. The generator will go to full output. If it doesn't show a charge on the ammeter now, your generator is probably bad.