Generator run at different speeds

[supercub]

I have an Onan 7500 watt diesel generator.
With nothing on in the motor home, other then then items like the CO2 detector, the Microwave display, etc etc. the following is happening.
The generator will run at three different rpms (judging from the sound) At each level it will run for several minutes (5-10) then will switch to the next level. Kinda like shifting gears.
Inside the motor home I have a Xantrex display that shows DC Volts, amps and Battery State.
The Battery State displays 3 different battery levels. First indicator is an outline of a battery and shows a low level, next little battery shows a 1/2 level and the 3rd battery display shows a full battery.
When the generator changes rpm (power) the Battery State display will change also.
I don't recall my generator doing this before.
I did check the voltage at the batteries at they were all good.
Any ideas?
Thanks
Brian

PS This is on a 2004 Fleetwood Revolution.

[Passin_Thru]

Sure does, I have one. It should idle with just the load you have on it and go to full throttle with the air conditioner, microwave and TV on. Load test batteries.

[wolfe10]

KD4UPL wrote:

wolfe10 wrote:

rgatijnet1 wrote:
The sound of the generator will change as the load increases or decreases but the RPM's are what determines the 60 cycle AC output. The RPM's should remain constant, with a small jump as the load changes.

No, not for this particular generator. RPM DOES vary with load.

Which "particular" generator is this? There are Onan diesel generators that do very their RPM. I don't know if the OP has one of these or not and apparently he doesn't know either.
OP, Do you have the exact model number of the generator? Some are supposed to very the RPM and some not.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0ahUKEwiwtYnOs9jWAhUX3YMKHY9ECbk...

From that Onan pdf:
Computer-Controlled Variable Speed Operation Matches Engine Speed to Load Demand, Minimizing Noise Level

[Roger_in_VERMON]

We have the same generator. That sounds normal to me. Batteries get charged the refrigerator also takes quite a bit of power.

[KD4UPL]

wolfe10 wrote:

rgatijnet1 wrote:
The sound of the generator will change as the load increases or decreases but the RPM's are what determines the 60 cycle AC output. The RPM's should remain constant, with a small jump as the load changes.

No, not for this particular generator. RPM DOES vary with load.

Which "particular" generator is this? There are Onan diesel generators that do very their RPM. I don't know if the OP has one of these or not and apparently he doesn't know either.
OP, Do you have the exact model number of the generator? Some are supposed to very the RPM and some not.

[ArchHoagland]

How old are the batteries and how many batteries do you have?

[time2roll]

supercub wrote:
The Battery State displays 3 different battery levels. First indicator is an outline of a battery and shows a low level, next little battery shows a 1/2 level and the 3rd battery display shows a full battery.
When the generator changes rpm (power) the Battery State display will change also.
I don't recall my generator doing this before.

Sounds normal. I suspect the indicator is telling the charging stage of bulk, absorption, and float. Depending on equipment the generator load could be 18 amps down to 2 amps as the battery charges and the system changes voltage. Yes it may indicate a growing issue with the battery such that it was not noticed before. Or the battery was a bit lower on charge this time.

[OLYLEN]

Sounds normal to me. There are small loads all the time and the Gen is responding to those loads. As above KILL-A-WATT will tell voltage and cycle and if you plug things it it will tell load. Refer, hot water on, TV, SAT, anything?

LEN

[wolfe10]

rgatijnet1 wrote:
The sound of the generator will change as the load increases or decreases but the RPM's are what determines the 60 cycle AC output. The RPM's should remain constant, with a small jump as the load changes.

No, not for this particular generator. RPM DOES vary with load.

[wallynm]

Onan vary the RPM depending on load.

[mccsix]

The cycling tells me that that the gen is operating the way it should but the batteries are suspect. I agree with a load test to test their condition.

[rgatijnet1]

The sound of the generator will change as the load increases or decreases but the RPM's are what determines the 60 cycle AC output. The RPM's should remain constant, with a small jump as the load changes.

[supercub]

Trackrig wrote:
I have a 2005 Fleetwood Excursion with the same generator. With nothing else on, the generator rpms will change and the needs of the batteries / battery charger change. The rpms will start off somewhat higher when the batteries first start charging - drawing a higher amperage. Then as the batteries have been receiving a charge, the charger amperage decreases and therefore the generator rpms decrease.

I don't see any problems with your generator. The same thing happens when the A/C or microwave comes into use.

Bill

Thanks Bill, the trouble is, it will keep going through these cycles, over and over and over again.

[Trackrig]

I have a 2005 Fleetwood Excursion with the same generator. With nothing else on, the generator rpms will change and the needs of the batteries / battery charger change. The rpms will start off somewhat higher when the batteries first start charging - drawing a higher amperage. Then as the batteries have been receiving a charge, the charger amperage decreases and therefore the generator rpms decrease.

I don't see any problems with your generator. The same thing happens when the A/C or microwave comes into use.

Bill

[rgatijnet1]

Buy one of the inexpensive Kill-A-Watt meters and when your generator is running, this will tell you the exact voltage and frequency of your generator output. it should be a constant 120 volts at 60 cycles. Kill-A-Watt