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Hi to all. I'm trying to refurbish this old JD that my mother used. I've got it running and all the belts replaced. My situation now, and for quite a while, is that the battery isn't charging. I am getting 28 vac out of the stator, which I think is normal. The voltage/rectifier only puts out 11-12 volts. I've tried three different regulators, the original, a brand new one I bought, and one off a friends engine with the same 41 403 09 regulator which is working fine. All three put out the same 11-12 volts. I have checked for bad grounds, found none. Everything I've read, says if I'm getting aroung 30 volts ac from the stator and less than about 13-13.5 volts dc from the regulator, the regulator is bad. I can run it with a fully charged battery for quite some time, then the amber battery light comes on. Does anyone have another idea on this? Thanks for any and all advice? Roy

Two things to check. Are you getting battery voltage on the B+ wire at the regulator. And make sure that the ground wire/strap is present from one of the regulator mounting bolts and one of the blower housing bolts. If the regulator isn't grounded it won't charge the battery. If both those things check out try running a wire from the B+ terminal of the regulator directly to the B+ terminal of the battery. Could be a bad wire that won't carry current to allow charging.

Thanks for the reply. I've checked that the regulator is grounded and the ground wire is attached and properly grounded, 0 ohms to ground. I am getting battery voltage to the regulator 'B' terminal. I'll run the extra wire from regulator 'B' to battery + and post results.

I ran a jumper wire from regulator 'B' terminal to the battery +. Used a Fluke digital multimeter to check the voltage. Before cranking, I had 12.01 volts on the battery. With the engine running, the voltage dropped to 11.85 volts. This was the result with or without the jumper from regulator to battery. Turning the engine off, the battery voltage came back to 12.00 volts.

Back of my mind I am thinking loose flywheel magnets, but I don't think you would get 28 AC from the stator with the magnets loose. Could be weird battery issue, but that is about as strange as 28 AC with loose flywheel magnets.

Yep, don't think I'd have 28 vac with loose magnets, may pull the flywheel just in case. First, I'll try another battery. Thanks for the idea.

Ok. Just tried another battery. It had 13.11 volts with the engine off. With the engine running, it dropped to 12.74 volts. Different numbers but same result.

relhok said:

I have checked for bad grounds, found none.

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How was this check done specifically? Visual? Hand tug on the cable?

Might need to do a load test, voltage drop check see. Circuits need to be loaded to verify proper functioning.

You have 28VAC from the charging coil. Tried 3 regulators and tested grounds. To me, from what you wrote, the positive side is working. Negative side is suspect.

This video is the theory behind voltage drops. Some of the video I don't agree with. Still need to do with with a LOAD applied.

Hi slomo and thanks for your interest and ideas. I use a Fluke(which the name doesn't reflect on the meter's performance), digital multimeter for all measurements. If it reads 0 ohms, there's no resistance. For both you and ILENGINE, I just pulled the flywheel and checked the magnets. No loose ones. Cleaned them up a bit, also blew debris from around the stator. All looked good. Put all the pieces together again. Checked stator output again, now I get 40 vac instead of 28 volts earlier. Put the regulator back on, put meter across battery, got 13 volts with engine dead. Started engine and voltage dropped to 12.7 from battery + to - and also from regulator ''B' to ground. Slomo, I'm not familiar with positive side vs negative side or how to isolate one from the other. I'll watch the video and see if that helps. Thanks again.

If you have 40 volts AC and 12.7 volts DC then that would indicate a bad regulator. They do make a tester to test the regulator but most people don't have one like I do where I work. Like ILENGINE said make sure that the ground wire/strap is present from one of the regulator mounting bolts and one of the blower housing bolts.

slomo said:

How was this check done specifically? Visual? Hand tug on the cable?

Might need to do a load test, voltage drop check see. Circuits need to be loaded to verify proper functioning.

You have 28VAC from the charging coil. Tried 3 regulators and tested grounds. To me, from what you wrote, the positive side is working. Negative side is suspect.

This video is the theory behind voltage drops. Some of the video I don't agree with. Still need to do with with a LOAD applied.

Click to expand...

slomo said:

How was this check done specifically? Visual? Hand tug on the cable?

Might need to do a load test, voltage drop check see. Circuits need to be loaded to verify proper functioning.

You have 28VAC from the charging coil. Tried 3 regulators and tested grounds. To me, from what you wrote, the positive side is working. Negative side is suspect.

This video is the theory behind voltage drops. Some of the video I don't agree with. Still need to do with with a LOAD applied.

slomo said:

How was this check done specifically? Visual? Hand tug on the cable?

Might need to do a load test, voltage drop check see. Circuits need to be loaded to verify proper functioning.

You have 28VAC from the charging coil. Tried 3 regulators and tested grounds. To me, from what you wrote, the positive side is working. Negative side is suspect.

This video is the theory behind voltage drops. Some of the video I don't agree with. Still need to do with with a LOAD applied.

Click to expand...

Click to expand...

hlw49 said:

If you have 40 volts AC and 12.7 volts DC then that would indicate a bad regulator. They do make a tester to test the regulator but most people don't have one like I do where I work. Like ILENGINE said make sure that the ground wire/strap is present from one of the regulator mounting bolts and one of the blower housing bolts.

Click to expand...

Easy way to check is to set your meter to DC volts and touch the red lead to the metal housing of the regulator, and the black lead to the engine block. See what the voltage is. Should be close to 0.

It sure looked like a bad regulator to me, too. After trying 3 different regulators though, maybe not. I have checked that the regulator is grounded, 0 volts from regulator case to engine block, also 0 ohms. Have also checked connections between battery posts and their respective clamps, and loosened, cleaned and reattached the battery - cable to engine block. I'll have another 'new' regulator this week, I'll post the results after it's installed.

98% of people overlook the grounds. Initial diagnostic testing always starts on the + side, for some reason??.

On mowers you need to check the engine mount to mower frame bolts are present and tight.

Some mowers will install the ground cable from the - batt post to the mower frame. Relying on rusty engine mounting bolts, paint and rusty frames to provide a poorer path back to the battery. They do this as it makes the ground cable shorter and long story short CHEAPER.

In reality, ground cable should go from batt - to the starter housing. Why? The starter is the highest amp draw device on a mower. Connected this way provides the best path for the starter to spin faster. Starter will perform better and last longer/run cooler with a better ground.

Looking at ground paths. A steel mower or car frame, with CLEAN bare metal connections carries current at a 70% value. A clean over amp rated/sized full copper wire is valued at 100%. So a clean steel frame connection starts out inferior. Then you add paint and rust...... Copper is better than steel as we all know.

You need to research star grounding washers, dielectric grease, hydraulic crimp tools and full copper lug connectors.

If you want a little more info, watch the below video. Look at WHAT they are trying to do and not HOW they do it. Most of these videos are wrong for this purpose. It's called the big 3 or big 4 upgrade.

Put the 2nd 'new' regulator on and got the same result. Battery voltage started at 13.2. Started the engine and voltage dropped to 12.5. Guess it's not a regulator problem. I'm looking at the grounding possibilities now. Thanks ILENGINE and slomo for your advice.

My Kohler was not charging. All the magnets rusted off the fly wheel.

I finally found my problem. There are several sites that suggest unplugging the regulator/rectifier connector and checking stator output with engine running full speed. That's fine and well but you should then turn the engine off, reconnect the regulator connector, start the engine, run at full speed and check the stator output again. It should be around 30 vac or more. I did this and the stator output was 0 vac. This step is omitted on most forums. I also had failed to take notice of the stator resistance, which should be nearly 0 ohms, mine was much higher. I pulled the stator for inspection again. I saw a few specks of greenish corrosion, and looked at these with magnifying glass. Two of these areas had almost 'eaten' thru the copper winding. I removed these sections and rewound with good wire. May not be long lasting but it worked. After reassembly and with the regulator connector plugged in and engine at full speed, I had 30 vac from the stator and 14.5 vdc on B+. Hope this helps someone who has a charging problem.