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I have done everything I can think of to correct a ZMaster that is not charging.
Stator is giving off greater than 27 volts
Checked rectifier with Ohm meter. Checks out OK
Took battery to have it checked, checks out OK
The ground from the battery to block and solenoid look OK.
With key on DC wire at rectifier is putting out 12.4 volts.

I just can't get 13-14 volts to the battery while running.

Is the ground strap that goes from the regulator to the block attached and in good shape. If the regulator isn't grounded it doesn't work. AC output from the stator should also be 28 volts or above.

If voltage is less than 28 volts, stator is probably faulty and should be replaced. Test stator further using an ohmmeter.

With engine stopped, measure the resistance across stator leads using an ohmmeter. If resistance is 0.064/0.2 ohms, the stator is OK.


1, bad stator
2, bad rectifier/regulator
3, bad battery
4, bad wiring

ILENGINE said:

Is the ground strap that goes from the regulator to the block attached and in good shape. If the regulator isn't grounded it doesn't work. AC output from the stator should also be 28 volts or above.

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Thanks, the ground wire is in good shape and connections are good.
I am getting 28 volts and as I increase rpm's the voltage increases. It doesn't appear to be the stator.

EngineMan said:

If voltage is less than 28 volts, stator is probably faulty and should be replaced. Test stator further using an ohmmeter.

With engine stopped, measure the resistance across stator leads using an ohmmeter. If resistance is 0.064/0.2 ohms, the stator is OK.


1, bad stator
2, bad rectifier/regulator
3, bad battery
4, bad wiring

Click to expand...

You listed my check list. Checked everything on the list. With switch on and connector off i am getting voltage of 12+volts from the DC wire. Meaning there is no short between rectifier and battery.
I did an ohm check on the rectifier and it I am getting an infinity reading with red on + and black on both AC. Getting a 168.8 ohm on both AC connections with black on + and red on AC.
Haven't done an ohm check on stator but voltage is good with engine running. I am going to take the rectifier to a shop with a Kohler rectifier reader. I am puzzled

So what to get between the + output of the rectifier and ground.
Wire connected should be battery voltage engine off & output voltage engine running.
Some run the output through the ignition switch while others plug the output directly into the battery.
Very common to find the purple wire burned out at the ignition switch.

bertsmobile1 said:

So what to get between the + output of the rectifier and ground.
Wire connected should be battery voltage engine off & output voltage engine running.
Some run the output through the ignition switch while others plug the output directly into the battery.
Very common to find the purple wire burned out at the ignition switch.

Click to expand...

Thanks,
My DC goes to a 30Amp fuse and another wire off to solenoid.
I was going to do that tomorrow. I am going to connect to the rectifier and check voltage with switch on and turn it over to see what voltage rectifier is putting out.

I am having the same problem with my Z-master with a CH20s. My stator is only giving off 26v ac so new stator is on order and the engine is going to be pulled.

bertsmobile1 said:

So what to get between the + output of the rectifier and ground.
Wire connected should be battery voltage engine off & output voltage engine running.
Some run the output through the ignition switch while others plug the output directly into the battery.
Very common to find the purple wire burned out at the ignition switch.

Click to expand...

I took the rectifier to a shop that has a kohler rectifier check tool. The rectifiers are good as my ohm test reflected. I ran a ground from the rectifier to the battery and I am still only getting 12+ volts back to battery. I am getting 12+ volts off the DC output with engine on. This should mean there are no ground breaks. I am getting greater than 27 volts as I ramp up the rpm's.
I am still puzzled.

A couple of dirty contacts will knock the stuffing out of that 27 V AC

Bad contacts between the stator & the ground ( via mounting bolts ) is a prime place.
In theory 27 V AC should equal 13.5 V DC.
In reality this never happens as there are losses everywhere, heat for instance.
While the NOMINAL voltage is 12 V the actual voltage is 13.2 V ( 6 x 2.2 V ) and you need 13 V minimum to recharge the battery.
So your stator output is probably sufficent to run the mower, without draining the battery, it will not be enough to recharge it.

There was a factory service notice for several mowers to move the DC feed wire from the rectifier to bypass the ignition switch because of voltage losses in the switch.

Any time I can not get 28V AC from an alternator it gets replaced.