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This engine is on a Toro Proline 30159. It's the model with the electric clutch that runs directly off the charging system, no battery.

Does anyone know what the input voltage and output voltage for the regulator/rectifier should be? At full throttle, I'm getting about 48V AC in and 24-28V DC out. This is a brand new, genuine Kohler voltage regulator. Seems high to me, but I've never worked on one of these battery-less systems before.

Just trying to make sure the charging system is putting out the correct voltage so it won't fry the new $250 blade clutch I'm getting ready to install.

Thanks!

AC voltage sounds correct to me, but DC output seems very high. Never work on a charging system without a battery. Most electric clutches I have worked on are rated at 14.5 MAX. I would temporarily install a battery in to system and see what the charging voltage is at the battery. If you still have that high of voltage at the battery, I would say you have a faulty regulator. Just my opinion. Here’s a manual. https://mymowerparts.com/pdf/Kohler...13-CV14-CV15-CV16-CV460-CV465-CV490-CV495.pdf

AC voltage sounds correct to me, but DC output seems very high. Never work on a charging system without a battery. Most electric clutches I have worked on are rated at 14.5 MAX. I would temporarily install a battery in to system and see what the charging voltage is at the battery. If you still have that high of voltage at the battery, I would say you have a faulty regulator. Just my opinion. Here’s a manual. https://mymowerparts.com/pdf/Kohler-...V490-CV495.pdf

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Thanks! Since there's no place to attach a battery from the factory, should I just wire positive to the B+ terminal on the regulator and negative to ground?

Hard to believe a brand new regulator is bad, but stranger things have happened...

Before you do anything find the brand name & numbers on the clutch.
Next search the manufacturers web site for the clutch specifications.
If the engine is batteryless Toro could have fitted a 24V clutch to reduce the amps needed to run it.
Regulators & rectifiers are happy playing with high voltage but not passing a lot of Amps.
Amps = heat and heat is to be avoided in circuits as much as possible

Toro's wiring diagram seems to indicate the system is 12v:



I also looked up the Ogura part number, and it's 12 volts. The regulator is new, and it is the correct part number for this model.

If it is a new engine, I suggest you have the charging system tested by an authorized Kohler dealer. If the system is not operating properly, it should be repaired under warranty.

I suspect a load is needed to get the voltage down to the rating on the clutch. Try an old headlight on the clutch terminals and check the voltage with this load, probably drop it to near the clutch coil rating without risking the actual part.

This evening, I attached my ATV's headlights to the blade clutch terminals. They came on briefly, and then blew the fuse (7.5 amps.) Looks like I will have to find a smaller load. According to Toro's wiring diagram, the clutch itself draws 2.98 amps.

Would I get a correct reading if I just hooked a 12V battery up to the blade clutch terminals? I don't have any old mower headlights just laying around, and all the other 12V loads I have would be too big.

EDIT: I do have a large computer fan that draws just under 1 amp. Think that would be big enough?

UPDATE: I wired the computer fan to the system this afternoon. It briefly brought the voltage down to 13-14 volts at 1/4 throttle, burned out the fan motor before I could test it at full throttle.

Then I connected it to a slightly discharged riding mower battery. Voltage stayed at around 20 volts, and after a few seconds it blew the 7.5 amp fuse.

I took the old blade clutch off, and it is indeed a 12 volt clutch.

What's next? Do I need to run another test, replace the stator, replace the voltage regulator, or...???

Sounds very much like your regulator is duff to me

bertsmobile1 said:

Sounds very much like your regulator is duff to me

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I'll replace it again and see if that changes things. The regulator on there now is a NOS one I got on eBay.

One more question, does 48 VAC sound right to you for the regulator input voltage? That's what the stator is putting out.

Yes, stators can produce 48 VAC even if the engine is running at normal speeds. Output is dependent on the size of stator. Regulator is designed to reduce it to 12.6-15.2 DCV. Agree with Bert, bad regulator.

Rivets said:

Yes, stators can produce 48 VAC even if the engine is running at normal speeds. Output is dependent on the size of stator. Regulator is designed to reduce it to 12.6-15.2 DCV. Agree with Bert, bad regulator.

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And the space between the stator & rotor which under normal production tollerances can vary quite a bit.
A really high voltage is usually because the rotor & stator are not fully concentric so one set of coils that are closer will pump out 48V while the others could be anything from there to 20V.
Because the engine is making 9,000 pulses a minute your meter simply reads the highest voltage.
When you connect to a scope you can see the voltage pulses that you can not see on a multi meter .
Back in the bad old days we used Zener diodes which go closed circuit at 14V so at 14V dc or higher the diode shorts out to the frame turning the excess voltage to heat.

With alternators, the speed & number of turns of wire determine the voltage.
The strength of the magnetic field determines the current.
There is a chance that your stator & rotor ( flywheel ) are not a set.
However to sort that out the mower will have to go to a dealer who can tell the difference between the 3 Kohler flywheels & the stators by sight.
AFAIK there are no numbers on the stator or flywheels.

The danger is if you have a mismatched set all you will do is burn out another regulator and they are not cheap.
Also if the alternator is is matched that is a warranty claim as some one stuffed up at the factory.