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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 27485
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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My SCQ STT61A-27KA sn# A6200274 which has the Kawasaki FD750

Customer Question

My Scag SCQ STT61A-27KA sn# ***** which has the Kawasaki FD750 AS08 engine is producing charging voltage of 15v. Failed PTO clutch brought this to attention, as well as blown 20a fuse. Battery tests good, all wiring and ground appear clean and solid. Stator output is 39-40 VAC. I replaced the regulator (Kawasaki OEM) with no improvement. When engine first starts the amp guage pegs positive then casually settles back to slight positive. Running volts hover at 14.9 to 15.4. My understanding is that the engine should be regulated to about 13.8. Where the heck do i look next for a problem.
The replacement PTO clutch I purchased documents very clearly that anything over 14v is unacceptable so I am reluctant to energize it at this point.
Submitted: 11 months ago.
Category: Small Engine
Expert:  Curtis B. replied 11 months ago.

Running voltage is not unusual at all, It will start out charging at a higher rate and drop down as the battery is charged. I never saw where over 14 volts would harm an electric clutch. Have you checked the voltage at the clutch harness to see if voltage is still at the 15 volt range? I think you concerns are for naught!

Customer: replied 11 months ago.
The voltage is consistently at 15V throughout the harness and remains there even after running for some time. This has been the case even after the battery came off a full charge from an independant charger. I spoke with the clutch manufacturer who was very clear that nominal voltage for the clutch was 13.8 to 14.2 and anything above that would prematurely fail the clutch primarily due to increased heat in the coils. Also according to them this engine regulator should have a set point at 13.8. And what about the huge AMP spike on startup, this is a new happening.
Expert:  Curtis B. replied 11 months ago.

Swap the battery , charging above normal is regulator trying to charge what it sees as a low battery Also check the battery ground, you can have a bad ground, and will cause overcharging.