Cummins Onan Onboard Generator Output

[CORattler]

I was doing some research on the Cummins Onan generators for RVs as that is a future purchase that I want to know more about. I looked at output based on temperature and altitude which are two things near and dear to the hearts of Colorado RVers. Interestingly enough, I came across this info:
Typical power output change based on ambient conditions:
– Temperature: Power output decreases 1% for every 10° F (5.5° C) increase
– Altitude: Power output decreases 3.5% for every 1000 ft (305 m) increase
Ratings represent minimums. Actual performance may be significantly higher based on installation and operating conditions.

Since we often stay at sites between 6000 to 9500 ft in altitude, I will need to take that into account when purchasing a generator so that adequate output will be available for our needs.

I'd like to hear from those of you that have a Cummins Onan unit that camp at these altitudes as to if/how those altitudes affected your units.

[bigmurf]

Keep in mind that LPG also takes away some of your rating. The good thing is we never needed the A/C at 10,000 feet and above.

[camper4]

We have camped at some high elevations and never noticed any difference in the Onan's operation. We have the 5500. But we typically do not use all the 5500 watt rating either.

[bncinwv]

I was thinking that all engines (gasoline, diesel, etc.) suffer from altitude effects as well. I don't know whether the efficiency decrease is comparable between the fuel types though?? Like others, even if your power output decreases 20%, you would still have 4000 watts of power which would cover practically every electrical load in the rig other than running dual air conditioners. There are amperage and wattage draw charts available which would give you a better idea of the total power needs that you would have.
Bingo

[TLightning]

As noted, at 10,000' a generator, or any normally aspirated engine, will have lost 1/3rd of it's power. Somebody needs to make a turbo generator that will run like our trucks.

[mlh]

All non turbo engines suffer the same power loss. Turbo diesel engines don't lose much power until about 12000 feet if their turbo is large enough. This is why the new Ford 6.7 doesn't perform as well as the new Chevy at high altitude. The Ford cant get enough air.
Lynwood