Calling all charging system gurus!!!!

[C5rider]

But, I didn't...

I went back and looked at the ground(s) at both the V/R and the S/G. I figured that since I repainted the S/G (it was off and available) that perhaps, the new coating covered the path of current to ground. So, I cleaned the mount for the ground cable (bolt at the rear S/G mount) and while looking at the V/R, I noted that the small ground strap was very brittle. So, I re-soldered a new on on and installed a star washer to help it bite into the metal at the mount.

Then, I took a reading after hooking the battery back up and engine running. Nuthin.

I've heard that it isn't necessary on S/Gs, but i decided that since I had the battery disconnected and removed the S/G, I'd polarize the S/G. After doing that, I started the engine and the DVM showed 14-ish volts! VOILA! It was now working!

Then, I idled it down to check the voltage and when I ran it back up --- Nuthin'

i shut it off, and sometimes when I'd re-start, it showed 13.5-14v, and other times... nuthin.

Even grounding the field terminal only shows 1.5-1.8v at the "A" terminal. My brother said that "it may be charged and may not NEED that much current." but I'm thinking that grounding the "F" terminal would still make it charge fully, regardless of battery level, right?

R. Bedell,
Grounding the "F" terminal directly to the battery would also negate the ground path between the V/R and generator also, right?

In the middle of learning a LOT about these little tractors and their charging systems.

Thanks for the insights!

[JayJay]

I'm certainly as attentive to the experts as C5Rider, because I like to understand how things work, and I've learned much from the explanations thus far. However, one could take the "practical approach" and run the tractor over a period of time in order to see if the charging system is working "well enough" to get by, and perhaps, as your brother contends, it is working as designed.

[R Bedell]

Sounds..............like an intermittent wire connection somewhere. Start the tractor and hook up and volt meter across the battery terminals. Start wiggling charging circuit wires and watch the meter. You might find the connection that is bad.

[save_old_iron]

Originally Posted by C5rider

But, I didn't...

Even grounding the field terminal only shows 1.5-1.8v at the "A" terminal. My brother said that "it may be charged and may not NEED that much current." but I'm thinking that grounding the "F" terminal would still make it charge fully, regardless of battery level, right?

Grounding the "F" terminal will cause the SG to output full power irregardless of the battery state of charge. You should see at LEAST 15 - 16 volts from the "A" terminal with the field terminal grounded and engine running 3/4 throttle or above. Maybe a cold solder joint on the F terminal stud inside the SG motor? Flashing the field may have temporarily healed a cold solder joint in the field circuit and allowed the SG to temporarily come back to life. The field coil resistance measurement you made with an ohmmeter will not stress the integrity of the cold solder joint like actual operating current will. The ohmmeter only puts microamps of current thru the F terminal connection vs 2 - 3 amps when you ground the field.

I agree with Roland, sounds like an intermittent connection somewhere. Both the ground wires AND the battery (+) connection to the gen and battery need to be in good condition.

@ Rowland - If you mean 14 AWG should be used inside the regulator unit, the wiring I refer to inside the unit only carries the current to the FIELD coil - the wiring can be substantially less than 14 AWG to carry the 1 - 3 amps of field coil current.

[C5rider]

Definitely learning a lot from this process, and hopefullly others who might have this problem (and stumble upon this thread) might also learn, and solve their charging issue as well. Thanks for helping that happen!

I was of the mindset as Save_old_iron and when I grounded the field coil, as that eliminated most (if not all) of the wiring harness. Therefore, an intermittent wiring fault would pretty much be limited to the wire leading from the generator to the (-) side of the battery or inside the generator.

I'll start with the ground cable and work my way inside.

As they say, film at eleven!

[save_old_iron]

Originally Posted by C5rider

I was of the mindset as Save_old_iron and when I grounded the field coil, as that eliminated most (if not all) of the wiring harness. Therefore, an intermittent wiring fault would pretty much be limited to the wire leading from the generator to the (-) side of the battery or inside the generator.

The wiring to the field, armature, to and thru the tractor chassis, and battery all have to be in good shape for the SG to charge with the field grounded. However, the SG is acting as motor to start the engine. Sooooooo... that leads me to believe the main battery cables to the chassis and to the SG are good.

I'm betting my lunch money on something internal to the SG. As you said - we will see later on today.


Chuck

[C5rider]

Had a chance to spend a little bit of time on it over lunch.

I can't say that I fixed anything, but I did look around inside. I checked all the wires to be sure that they weren't rubbing the case, and i checked the coils that they weren't an open circuit.

I do have one question though. I hooked up my test light to the "F" terminal and when I touched the (-) battery terminal, nothing happened. BUT, when I touched the (+) terminal, the light lit up.

Does this show that the field coil(s) are shorted? Would that allow that they would not produce current? They did this with the engine running and with the key off.

Thoughts?

[C5rider]

I had a little bit of sunlight after work and decided to bite the bullet. I went out and decided to swap out the wiring.

I followed R. Bedell's wiring schematic for the Original and installed the other voltage regulator (almost new) that came off of my other original. There were a few things that I wanted to clean up about the way the previous owner had things wired, I was just hoping to wait until I tore the tractor apart to make those full-on changes.

I decided to make them now and remove the old, scraggly-looking wiring in hopes that the issue I was having would go with them. I ran 8-gauge for the starter button and battery (+) and (-) and 12-gauge for the rest of the system.

i don't know if it would have helped or not, but I checked the system with a digital multi-meter before hooking up the battery terminal solidly. I hooked up one terminal and then put the DMM between the other terminal and the battery wire. My thought was if there was a short, this would show as current without the solid connection (and possibly smoke something). Like I said, not sure if it would have helped but...

I didn't have any problems so I hooked up the battery. I fired up the engine and it was charging fine. I was happy!

Then I shut it off. And it didn't!

It kept idling (chug, chug, chug... )

I thought that was wierd. I turned the key back on and it chug, chug, chugged a little quicker...

Turn it off, and it chug, chug, chug...

So, I pulled the spark plug wire...

Chug, Chug, Chug..

Then I thought: It's feeding the starter! So, I pulled the (-) battery terminal and that shut it off. Had me going for a minute.

I unhooked the armature terminal from the S/G and tapped the wire to the battery terminal to see if I could hear the relays in the V/R making and breaking. After a few taps, they quit clicking. I tested them a few times afterward and couldn't get them to stick again. This was with the key off.

I turned the key on and things worked as normal. I checked it a few more times and they worked when they should, and didn't when they shouldn't. Plus, it was charging!

Had my head scratching for a few minutes there!

Thanks for the help, and the moral support.

[save_old_iron]

Originally Posted by C5rider

Then I shut it off. And it didn't!

It kept idling (chug, chug, chug... )

Ah yes - say hello to your newest friend, the CUTOUT RELAY in the regulator.

The cutout relay contacts are normally open until the engine is running fast enough to run the SG at a speed which allows the SG to switch over from being a "starter" to becoming a "generator".

When the engine / SG running fast enough for the SG to generate approximately 10 volts or more output,
the CUTOUT relay windings are energized by the SG's 10 volt + output and the contacts of the cutout relay then CLOSE - allowing the SG generator power to flow thru the regulator to the battery.

Think of the cutout relay contacts as an electrical bridge between the battery and the generator.
Backing up half a step, when the SG is used as a starter, engine speed is low so the cutout relay is NOT energized and the bridge between the battery and SG is open. This is normal.

So let's say the engine doesn't start and you shut off the ignition switch. NORMALLY the cutout relay contacts are open (remember no SG output = cutout relay contacts open). If the cutout relay contacts are open (as they should be), there is no electrical connection between the battery and the SG at this time. Follow the black arrows below - the SG is disconnected from the battery by the open circuit at the cutout relay contacts).





Now let's say the cutout relay contacts are pitted and they happen to stick together (not normal operation). There is now an electrical bridge between the battery and the SG and the connection remains intact even tho the ignition switch is off - battery power is now back-fed to the SG and allows the SG to become a starter again. Chug Chug Chug.

You are lucky the tractor was not in gear. I have seen tractors parked in sheds in gear walk out of the sheds by themselves if the cutout relay sticks.

And BTW, if you start messing with the regulator and accidentally close the cutout relay contacts with your fingers, the tractor will start to crank - and you won't be able to stop it until you open up one of the battery cables or physically separate the cutout relay contacts. Why? Because when you close the cutout relay contacts by mistake and the sg becomes a starter, current thru the cutout relay windings is now high enough to energize the cutout relay and keep the contacts closed !!

Both of these are hard to do if you left your tractor in gear and you are now chasing it across your lawn into your neighbor's yard !!

Another point while we are discussing this - the "back- feed" path thru the cutout relay was not meant to handle the load of the SG starter current. Backfeeding the SG in this manner is harmful to the relay coils in the regulator unit. Extended "back feed" cranking can overheat and destroy the coil windings in the relays in the regulator unit. The starter current was meant to be bypassed around the regulator and handled thru the starter relay wiring (in green below).





and that is all your going to get at 3 in the morning. Let me know if you have questions.

[C5rider]

Excellent explanation Save! That helps explain why there isn't any current flowing through the blue wire in R. Bedell's wiring diagram (which I'll include in this post, but can't take credit for) with simply the key on.

I knew that the starter button prevented any current from flowing through the heavy red wire to the S/G (if it's working properly) and wondered how the blue wire was energized, if it didin't have any current with the key on, engine running.

This helps me understand why (at 6am).

Thank you!

As soon as the neighbors are up, I'm heading back out there to make sure that it hasn't forgotten how to charge!