Monday, December 5, 2022


RV generator blues: High temps and altitudes



By Russ and Tiña De Maris

Generator: m01229 on Hot smiley: Chrkl on wikimedia commons.

Traveling in Oregon’s high country in the height of summer may be hazardous to your comfort.

Well, actually, traveling anywhere at high altitude, in high temps, if you’re depending on a generator to run your air conditioner, can lead to disappointment. We found this out when at 5,000 feet, and 105 degree weather, and our faithful Yamaha suddenly turned “faithless.” Or so it seemed.

For most of us, our generator is a simple beast, not like modern day internal-combustion units that come equipped with “smart” stuff like oxygen sensors and systems that adjust for varying conditions. So here are some fun facts that may turn out to be not-so-fun:

Once you hit 500 feet above sea level, engine power decreases 3.5 percent for every 1,000 feet of increased altitude. With us at 5,000 feet, our little generator was suffering a rough 16 percent power loss. Strike one. Then bring in the heat factor. Engine power decreases 1 percent for every 10 degrees in temperature increase above 85 degrees Fahrenheit. Sitting at 105 degrees, we were then 20 degrees above the magic number, meaning an additional 2 percent power loss. A total of 18 percent “less available” power.

And never forget to figure in the stupidity factor. Our generator is mounted in the back of our towing pickup — equipped with a canopy to keep everything safe and dry. Normal operations call for us to open the canopy lid and drop the pickup tailgate while operating the generator. But when you’re tired from the road, ready to get out of the heat, leaving the tail gate shut (even with the canopy lid up) can quickly increase the generator temperature and, in turn, decreasing the power efficiency in a big hurry.

In the end, it all added up to several very uncomfortable hours of no air conditioning. Good old Yamaha turned to “Yammer-ha” when there just wasn’t enough power left to overcome the resistance of our air conditioner. We ran a fan and drank plenty of water until things got back to normal.

Lessons learned: When figuring how much muscle you need in your generator, add more if you plan on any high country travel.


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Sherry Dawson
5 years ago

You comments all appear to be addressed to using portable generators. Do the same problems occur with the larger generators built in to motorhomes, fifth wheels, and newer trailers?

Mike Sherman
5 years ago
Reply to  Sherry Dawson

Probably not Sherry. The portables put out less power, whereas most RVs with built-in generators are rated around 5,000 watts. General rule in my humble opinion is you can never have too much power.

Jonathan Miller
5 years ago

Makes you wonder why generators are still being designed with 50 year old technology? Carburetors and mechanical ignition systems are primitive by any standard. Not to mention the 3600 constant RPM and analog control of frequency. Seems to me there is a demand and market for more advanced generators, but I haven’t seen any. At least not the built-in type for motorhomes. As much as these things cost there is no excuse for them to be using 50 year old technology.

Tommy Molnar
5 years ago

When you LIVE at 5,000+ feet, I would hope that generators you buy locally at this altitude would already be adjusted for this. But, probably not huh. They just ship them in from wherever and put them on the shelf.

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