Kohler 12.5

[Bitternut]

I have a Kohler 12.5K genny on my recently purchased Newell Classic and I am wondering about how much fuel consumption she will require per hour of normal use without running A/C and maybe how additional it might take when A/C is running. I'm assuming that if I was running A/C in the summer that the RPM's would increase under a higher load, am I correct?

[fulltiming]

Bitternut, welcome to NewellClassic.com.

It is better to run the genset, as with an diesel engine, with a load on it than without a load. The generator should be turning at a constant speed to generate a constant 60 Hz regardless of the load.

I find that my 12.5kw uses about .63 gallons per hour of diesel typically running one or two AC units. With no load, fuel consumption would likely be almost the same.

[Bitternut]

Thank you fulltiming for you quick reply. So it sounds as if a big genset like this can get almost 2 hrs on a gallon. That's not too shaby. You don't think that at a lower rpm the fuel consumption would be less I'm gathering?

[fulltiming]

I'm assuming that if I was running A/C in the summer that the RPM's would increase under a higher load, am I correct? No, the generator governor will keep the engine at a constant speed. The generator will slow down momentarily when a large load is added but the governor will bring the engine speed back up again almost immediately. Lowering the speed of the diesel generator by adjusting the governor would mess up the quality (voltage and frequency) of the power the generator is turning out. You don't want to do that. The fuel consumption would not decrease significantly and the lower voltage and frequency of the power would start messing up electronics, potentially overheating components such as air conditioner compressors, and anything that was frequency driven run slower than it should.

Most diesel generators run at 1800 rpms.