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Running a Generator at High Altitude: Tips and Tricks

If you're an avid RVer, camper, or just a fan of the heady feelings that come with altitude sickness, you know that being up in the mountains brings its own unique set of challenges, and running a generator is no exception. Here, your friends at WEN have prepared some handy advice about getting the most from your generator no matter the environment.

High-altitude kits

One of the most important bits of gear you can have when bringing a generator with you on your high-flying adventures, a high-altitude kit will help you squeeze every watt of power out of your WEN generator. 

An example of a typical WEN high-altitude kit.

 

Many WEN generators come with at least one high-altitude kit, and we offer a high-altitude kit for every generator we sell. Each kit consists of a carburetor jet, a bolt gasket, and a bowl gasket. The kit is installed in the carburetor, and adjusts the fuel-air mixture so it's optimized for the lower air pressure found at higher altitudes. Most WEN generators have kits optimized for use between about 3000 - 6000 feet (914 - 1828m), and another for 6000 - 8000 feet (1828 - 2438m). Check the specific altitude ranges that come with your high-altitude kit.

Failure to use a high-altitude kit can cause your generator to run rough, perform weakly, or even suffer damage. Similarly, leaving a high-altitude kit installed at low altitudes can also cause damage. WEN recommends that all high-altitude kits be installed by a professional mechanic. For more information, refer to your generator's owner's manual.

Derating

At higher altitudes, there is less air pressure than at sea level, as well as less oxygen. The thinner air causes engine performance to drop and fuel consumption to increase. Even with a high-altitude kit installed, though, the engine's performance will still decrease - the kit just helps limit the decrease. As a general rule of thumb, the power loss for every 1000 feet (305m) above sea level is around 2 - 3.5% with a high-altitude kit installed. So at 5000 feet, the engine would lose between 10% - 17.5% of its power. Without the kit, the losses would be greater.

Additionally, the engine's performance will drop when the ambient temperature is very warm. For every 10 degrees Fahrenheit (~5 degrees C) above about 75 degrees F (~24 degrees C), the engine's performance will drop by 1% - 2%. So on a 95-degree day, the engine would suffer a 2% - 4% drop in performance, compared to a cooler day. 

Adjusting expectations of the generator's performance is called derating. The altitude and temperature effects can be added together to get a rough estimate of the generator's derated maximum wattage. For example, let's say it's a 95-degree day in Denver, around 5000 feet of elevation. A generator in those conditions will suffer a loss of about 12% - 21.5% of its power, compared to that same generator at sea level on a 75 degree day. 

It's a good idea to keep the worst-case scenario in mind when choosing a generator. If you'll regularly be taking your generator up to high elevations, or running it on very hot days, you'll want to plan accordingly. To do so, follow the steps below. 

  1. Determine how much power you'll need on a continuous basis. For example, let's say you'll need 4000W.
  2. Add a little extra (10% - 20%) to make sure you have enough power for unexpected needs. WEN recommends that our generators be run at or below 90% of their rated power as often as possible to maximize their service life. With our 4000W example, another 10% - 20% would be 4400 - 4800W. We'll choose 4500W as a nice round number.
  3. Calculate the derating factor based on heat and altitude losses. In the example above, it was about 20%. Subtract that number from 1 (in this case, 1 - 0.20 = 0.80). Divide your wattage by that number (4500 / 0.80 = 5625W), and that's your final number. Choose a generator rated to at least 5625W

NOTE: the numbers above are an example, and are intended as a general guideline for making rough estimates. They are not hard-and-fast rules applicable in all situations at all times.

Dual-fuel and LPG generators at high altitudes

As mentioned above, the high-altitude kit helps adjust the fuel-air mixture and  achieve the air pressure that the engine needs to run its best. For that reason, WEN recommends that you always install a high-altitude kit when operating your generator at high altitudes, regardless of the fuel type (gasoline, propane, etc.) being used, and always uninstall it when returning to lower altitudes (below 2000 - 3000 feet). There's no need to adjust the fuel mixture or the propane regulator(s) - just install the high-altitude kit.

Also, keep in mind that even if you don't use gasoline, you'll still use more fuel at high altitudes than at sea level. 

Summary

Thanks for reading! We hope you found this article helpful, and are more confident about operating your generator wherever your adventures take you.

For more information about high-altitude kits and operating your generator at high altitudes, consult your generator's owner's manual, as well as the instructions that came with your high-altitude kit. If you have any questions, feel free to give us a call at 1-800-232-1195, M - F, 8 - 5 CST, or drop us a message here to speak with our friendly and knowledgeable technical support team. Happy travels!

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