I just changed my governor control board on my Kohler 5.5 KCM21 genset because the genset was running at max throttle. The new board fixed that problem and the genset engines idles down as it should. I went to try it with a load on but noticed that my old Magnetec battery charger which never charges above 13.3 v read 15.5 v. I read 120 vac in the outlet. I borrowed my friend's meter which measures HZ and volts. It just beeped and a fault light came on for HF( high frequency). I have three questions 1, Why does the battery charger read higher? 2, Can something other than the governor board cause this HF? The board is suppose to come from the factory preset, but it does have three pots that can be adjusted. 3, Or is this just normal and new boards need to be adjusted when first installed. I did turn off the circuit breakers for everything except the lights and converter before testing so hopefully there was no damage except my batteries being equalized.

Freq is too high because the engine speed is probably too high. I would talk to the factory rep and see what one of those pots controls engine speed. I am not an expert and my advice is, as they say, worth what you paid for it. Good luck.

If the frequency is high, so is the voltage. A frequency error won't fool a charger into excess output. Find a real meter that can read a wider frequency band and see what's really going on. We use those Kohlers in news vans and they simply die of old age.

SCVJeff wrote:If the frequency is high, so is the voltage. A frequency error won't fool a charger into excess output. Find a real meter that can read a wider frequency band and see what's really going on. We use those Kohlers in news vans and they simply die of old age. That is what I have always thought. But I checked it with two different meters and both read 120 vac. Also same two meters also read 120 vac when plugged into shore power and 60 hz on the meter. I tried readjusting the carb both main and idle jets but rpm stayed the same. Makes sense it rpm is high the voltage would be high but it is not.

What does the charger do when on shore power? There is always the possibility that the old Magnetec charger is having problems also.Since you don't have a frequency meter you can use a digital clock to check frequency but it might take an hour or so to show an error. A basic digital clock uses 60 Hz power as the timer. If the frequency is too high the clock will gain time. The clock on the coach microwave oven would work for this test. What I can't remember is how much error a 1 Hz change will cause.

electronic Automatic voltage regulation on the field will control the voltage even if the frequency is offHigh Freq does not mean high voltage when you have AVRGjac wrote:SCVJeff wrote:If the frequency is high, so is the voltage. A frequency error won't fool a charger into excess output. Find a real meter that can read a wider frequency band and see what's really going on. We use those Kohlers in news vans and they simply die of old age. That is what I have always thought. But I checked it with two different meters and both read 120 vac. Also same two meters also read 120 vac when plugged into shore power and 60 hz on the meter. I tried readjusting the carb both main and idle jets but rpm stayed the same. Makes sense it rpm is high the voltage would be high but it is not.

High frequency on generator | Good Sam Community

15 Replies

MrWizard
Moderator
Aug 01, 2015
electronic Automatic voltage regulation on the field will control the voltage even if the frequency is off
High Freq does not mean high voltage when you have AVR

Gjac wrote:
SCVJeff wrote:
If the frequency is high, so is the voltage. A frequency error won't fool a charger into excess output. Find a real meter that can read a wider frequency band and see what's really going on. We use those Kohlers in news vans and they simply die of old age.
That is what I have always thought. But I checked it with two different meters and both read 120 vac. Also same two meters also read 120 vac when plugged into shore power and 60 hz on the meter. I tried readjusting the carb both main and idle jets but rpm stayed the same. Makes sense it rpm is high the voltage would be high but it is not.
Dale_Traveling
Explorer II
Aug 01, 2015
What does the charger do when on shore power? There is always the possibility that the old Magnetec charger is having problems also.

Since you don't have a frequency meter you can use a digital clock to check frequency but it might take an hour or so to show an error. A basic digital clock uses 60 Hz power as the timer. If the frequency is too high the clock will gain time. The clock on the coach microwave oven would work for this test. What I can't remember is how much error a 1 Hz change will cause.
Gjac
Explorer III
Aug 01, 2015
SCVJeff wrote:
If the frequency is high, so is the voltage. A frequency error won't fool a charger into excess output. Find a real meter that can read a wider frequency band and see what's really going on. We use those Kohlers in news vans and they simply die of old age.
That is what I have always thought. But I checked it with two different meters and both read 120 vac. Also same two meters also read 120 vac when plugged into shore power and 60 hz on the meter. I tried readjusting the carb both main and idle jets but rpm stayed the same. Makes sense it rpm is high the voltage would be high but it is not.
SCVJeff
Explorer
Aug 01, 2015
If the frequency is high, so is the voltage. A frequency error won't fool a charger into excess output. Find a real meter that can read a wider frequency band and see what's really going on. We use those Kohlers in news vans and they simply die of old age.
gemert
Explorer
Aug 01, 2015
Freq is too high because the engine speed is probably too high. I would talk to the factory rep and see what one of those pots controls engine speed. I am not an expert and my advice is, as they say, worth what you paid for it. Good luck.

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High frequency on generator

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