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How do I troubleshoot my Kohler electrical system?
This frequently asked question was posted on the club's Discussion
board in the Clubhouse. Read the response from Al Eden, a long-time
Simplicity dealer (see more info). I've posted it here for easy access and reference.
Subject: Kohler Charging Systems
1/1/2001 8:12:46 PM
Hi, This post will address the problems and theory of the most popular Kohler
charging system. I intend to address the Briggs systems soon. They just have so
many different versions.
Kohler Charging Systems
The most common Kohler charging system is the 15 amp system, and I believe there
are a number of engines out there with 10 amp systems. The 10 amp system
is the same as the 15 amp system except the flywheel has one less magnet in
it. If you are looking at a Kohler flywheel that looks like that it is
missing a magnet, it is just a lower current system.
The system is pretty straight forward. There is a flywheel with a ring of
magnets on the inside that rotate around a multi-pole stator. The output
of the stator [2 wires] goes to a regulator rectifier and the output of that
goes to the battery.
To test the system the first step is to measure the voltage across the battery.
The standard voltage source to charge a battery without damage is 14.3 to 15.0
volts DC. This is true in cars, trucks, tractors, anything. Voltages higher than
that damage batteries. So you can use this test to check your car charging
system as well. If the system is putting a voltage in this range to the
battery it is working. If the voltage is lower than this several things
may be happening. The system may not have adequate capacity for the load
that it is looking at. Examples could be a whole bunch of lights added
etc. But with the lights turned off and just he battery you should see
this voltage with this system and the engine wide open. If you only measure
12.0V DC the unit is not charging. Shut the engine off and go to the
voltage regulator. In many of these engines it is now mounted in the fan housing
with 2 screws, with the fins inside the fan housing to cool it. In older
tractors ex 300 and 400 Acs the regulator was often mounted on the tractor, an
aluminum block about 3 by 4 inches with fins sticking up to cool it. On
the regulators there are 3 wires. Two wires come from the stator and are
the same color, one wire is the output to the battery. If the plug is flat
and all three wires are in line as most of the newer ones are, the 2 outside
wires are the stator leads and the center is the output. Some of the older
ones the plug is arranged in an L configuration. I havenít seen one of
these for a while and I canít remember which is which, but just look and see
which 2 wires come up from the flywheel area, these are the stator leads.
Now that we are at the regulator measure the DC voltage at the Battery Terminal
of the regulator. With the key turned on and the engine not running you should
see 12.0 VDC. This is the battery voltage. If not there is a problem
between the battery, key switch, ammeter and the regulator, as the battery is
not getting connected to the regulator. If you have 12.0Volts DC there, Start
the engine, open it wide open and measure the DC voltage on the battery terminal
of the regulator. If you have 14 to 15 VDC you have a bad connection
between the battery and the regulator. If only 12 VDC, shut the engine down.
Remove the plug from the regulator and start the engine with it running wide
open measure the AC [Be sure your meter is on AC VOLTS] voltage coming out of
the stator. You should have 28 volts AC or more. If you do, the regulator
is bad. If not, we will go to the next step.
Shut the engine off. Take an ohmmeter and measure from each stator lead to
ground, it should measure open or infinity. Next measure from one stator lead to
the other. This should not be more than a couple of tenths of an ohm. If there
is any leakage to ground or the resistance of the stator windings are high or
open there are 3 possibilities: (1) The stator is bad; (2) the leads coming from
the stator have contacted the flywheel and are either shorting to it, [leakage
to ground] or they are cut through, or (3) the stator is open. If the
resistance checks are normal and you didnít have the 28VAC, there are 2
possibilities. First if you are lucky, the stator may be OK and the
magnets may have come loose and are stuck to the stator and the flywheel is
turning around them. If this is the case: BEFORE REMOVING THEM, MARK THEM,
SO YOU CAN GET THEM BACK IN THE FLYWHEEL IN THE SAME SEQUENCE AND THE SAME SIDE
OUT!!!!!! You can then remove the glue remnants from the flywheel and
noting the stains glue them back in with epoxy glue. YOU MUST REMOVE THE GLUE
FROM THE MAGNETS BEFORE RE-INSTALLING THEM, OR YOU WILL NOT HAVE ENOUGH
CLEARANCE FOR THE STATOR!!! DO NOT LOOSE YOUR MARKS WHEN DOING THIS!!!
Glue them back in, in the same locations they were. If this is one of the
flywheels that is short a magnet glue them in with the same spacing and the skip
as before, use the stain marks in the flywheel. If they had a skip and you
just put them equally spaced around it will not work. If the stator is
undamaged put every thing back together and test her out. If the magnets
physically damaged the stator it will need to be replaced also.
If the flywheel magnets were OK, look at the stator and you may see windings
that have been hot and have the insulation burned off. This may have been
caused by something shorting out, causing the stator to overheat. If the
diode bridge in the regulator is shorted out is will cause this also.
Replace the stator and retest the system. If the regulator is shorted you will
find it as soon as you recheck the system. We have a regulator tester
[Kohler Special Tool] that will test the regulator, I would expect most Kohler
dealers would have this. It also checks the Tecumseh external regulators.
There are a couple of other Kohler charging systems, one a low current system I
have never seen and the other a 30 amp system that uses an external rectifier
bridge and a feed back coil in the stator similar to the control system ONAN
uses. This is only used on the K500 series engines and they are not used in
Simplicity and AC tractors, so I will not go there. Besides I am a very
I hope this is not too confusing, but I think it will cover 99.5% of the
problems you will encounter with Kohler charging systems.
My 2 cents worth and its free so value accordingly.