Starter generator not charging.

[tractor. 3]

Hey yall. So I have a wheel horse b80 with a kohler k181s with a starter generator.  (the engine was swapped at some point by the previous owner) the engine runs great, it starts up good, but its not charging, I have it all hooked up right, but its not charging enough to matter. I was just wondering do any of you know any problems I could be having, and how to go about fixing them. Thank you all.

[gwest_ca-(File Mod) 12,483]

This older Kohler service manual has a section on the starter/generator

 

[ri702bill 12,972]

5 hours ago, gwest_ca said:

This older Kohler service manual

The newer (cost reduced) regulators no longer have the nice screw adjustments. Instead, you have to bend the spring mounting tab to lengthen or shorten the springs to adjust to suit. A tedious process as a little is usually too much!

[squonk 48,056]

Make sure the short wire underneath the regulator that goes to the gen is broken.

[sqrlgtr 3,857]

1 hour ago, squonk said:

Make sure the short wire underneath the regulator that goes to the gen is broken.

pretty sure @squonk means not broken.

[adsm08 5,117]

First things first, and this thread seems to be skipping around. Diagnose, don't load the parts cannon.

 

1) Check the wire @squonk mentioned.

 

2) Take a base-line voltage measurement at the battery, with the engine off and  running. It should be near 13.5 engine running, it should not be less than the static voltage reading.

 

3) While running, measure voltage with the F terminal of the generator grounded. If the generator is working voltage should shoot up, and the engine should bog a bit. That indicates a regulator issue. 

    3A) If that DOES NOT happen, you have a generator issue.

 

If the test indicates a regulator issue remove the cover from the regulator and inspect for broken/burnt wires and carbon build up on contacts. It can also be informative to start the engine, with the cover off, in the dark, and look for arcing where it shouldn't be.

 

Since the regulator control voltage by dithering a set of contacts to control field coil ground carbon buildup on the contacts can negatively impact charging performance. The normal arcing that happens in this process can also wear the contacts, like a spark plug or set of points, making adjustments needed. Do NOT make adjustments with the engine running.

[FLtractor 219]

On 9/20/2026 at 6:16 AM, squonk said:

Make sure the short wire underneath the regulator that goes to the gen is broken.

Evening Squonk, my S/G for my K181 not turning over but was professional bench tested and it works but was told the voltage r regulator doesn’t charge. My question is the wire underneath my voltage regulator here.. does that anything to do with the starter turning over when key turned or that’s just the batter power- to ignition switch to the 2 terminal on the S/G to voltage regulator. Picture or my under wire appears tab not supposed be bent and wire may be frayed needed replacing 

[pfrederi 21,145]

That wire is what feeds the generator output to the regulator and then after the regulator regulates that out put it goes to the battery

[FLtractor 219]

20 minutes ago, pfrederi said:

That wire is what feeds the generator output to the regulator and then after the regulator regulates that out put it goes to the battery

So The battery powers the generator.. electrical current flows through that wire underneath to power the voltage regulator and then electrical current flows through the middle outside front terminal to the + battery terminal to keep it charged? So it’s a related self contained loop cycle if you will.. not sure if official electrical  term. 
If the powers flows into the voltage regulator underneath then what is wire going to terminal 1 here from voltage regular to S/G for?

Edited 4 hours ago by FLtractor

[squonk 48,056]

YOU STILL NEED TO CLEAN THOSE TERMINALS!

[FLtractor 219]

35 minutes ago, squonk said:

YOU STILL NEED TO CLEAN THOSE TERMINALS!

Yes I know and I will… I was wanting to understand more about the S/G and voltage regular areas in my post to you on here. 

Edited 3 hours ago by FLtractor

[953 nut 69,102]

1 hour ago, FLtractor said:

My question is the wire underneath my voltage regulator here.. does that anything to do with the starter turning over when key turned

No, the heavy wire from the battery "+" to the switch, the heavy wire from the switch to the S/G "A" terminal and the ground wire back to the battery "-" terminal are the only components in the start wiring. I run the ground wire directly from the battery to one of the S?G mounting bolts.

The diagram below should be helpful.

[FLtractor 219]

4 minutes ago, 953 nut said:

No, the heavy wire from the battery "+" to the switch, the heavy wire from the switch to the S/G "A" terminal and the ground wire back to the battery "-" terminal are the only components in the start wiring. I run the ground wire directly from the battery to one of the S?G mounting bolts.

The diagram below should be helpful.

So your diagram in conjunction with my 856 specific. Helps thank you.
on 856 diagram- what does the F terminal with wire to voltage gen front terminal on far right do? If power goes INto voltage regulator through terminal A. Does power go back into S/G through terminal wire F? 

[953 nut 69,102]

This B&S Manual gives a good explanation of how the S?G works.