Kohler Generator Voltage Irregularity

[tim.lesage@twc.com]

I recently purchased a 2002 Carver 570 Voyager. It has a Kohler 15.5 EOZ generator. When the boat was surveyed the surveyor noted the voltage needle to have some irregularity when it starts up, with voltage fluctuating between 220 and 280 V. The engine sounds quite regular during this time, and once the generator realizes its load it settles out at a constant voltage (takes less than a minute). The surveyor recommended having a generator specialist evaluate, which we did and they recommended some work including replacing belts and diodes on voltage regulator. $4000 later it still does same thing, and they now think it is insulation on the windings, which would be very expensive to deal with. The seller of the boat then sent out his own mechanic to evaluate (not sure of his true qualifications). His mechanic evaluated and replaced impeller and stated generator is working fine. He said voltage fluctuation is normal when generator is seeking out its load. i had another Kohler certified generator service evaluate after that to verify, but they said this degree of voltage fluctuation is beyond what would normally be expected. The sellers mechanic also mentioned that trusting the voltage needle that is on the panel may not be possible as it is a low quality indicator. Looking for advice/opinions on where to go from here. Money was escrowed upon closing to deal with things like this, but seller believes generator needs no more work since his mechanic stated it is fine. I have video showing the voltage needle during this period that I am happy to share with anybody that wants to see if. My dilemma is that I have had two separate Kohler certified service technicians say there is a problem, and one mechanic send by seller (who did seem quite knowledgable, but of unknown qualification) who says it is fine. I very badly want it to be fine so we can move on, but I believe it may not be. Relationship between me and seller/broker has unfortunately become a bit contentious. Any advice here would be greatly appreciated.

[bud37]

Sorry I can't say with any certainty , but I do understand engine speed governors....have any of them just checked the governor control on start up, if it is a spring type is may just be getting weak. Anyhow maybe a question to put forward as engine rpm control is necessary for stable operation of those things.

[km1125]

Source of the post... $4000 later it still does same thing...

YIKES!! That would piss me off if they did that much work and really had no clue that it would or wouldn't solve the problem!!

Source of the post
... and they now think it is insulation on the windings, which would be very expensive to deal with. ...

I cannot fathom a failure mode on the windings that would cause that kind of an issue.

Sorry I can't say with any certainty , but I do understand engine speed governors....have any of them just checked the governor control on start up, if it is a spring type is may just be getting weak. Anyhow maybe a question to put forward as engine rpm control is necessary for stable operation of those things.

There is at least one model of genset (I can't recall which) that uses an oil-filled governor. That oil is supposed to be changed periodically and if it's not then the governor is slow to react and will not compensate properly.

[ck36]

He said voltage fluctuation is normal when generator is seeking out its load.

I assume you’re seeing this behavior when starting the generator under no load?

The sellers mechanic also mentioned that trusting the voltage needle that is on the panel may not be possible as it is a low quality indicator.

Perhaps, but if it’s behaving consistently, it’s probably still an accurate indicator. For $4000 I would think the previous mechanics would have verified that the voltmeter was working correctly?

[tim.lesage@twc.com]

Yes, this behavior is noted when the generator first starts up, once AC devices (especially higher load ones like
HVAC) kick in if settles out and no longer fluctuates. It even
stays constant af that point if I turn off the load. I ordered a new voltage meter myself to try that out - should
have that by the end of the week.