How much Fuel does An RV Generator use? (8 Factors)

how much fuel does an rv generator use? (portable & onboard)

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Knowing how much fuel an RV generator uses can help you plan your upcoming boondocking trip accurately.

It can prevent situations like not being able to run your RV air conditioner due to a fuel shortage.

Or worst, being without power in the middle of your trip.

Knowing your generator fuel consumption rate will tell you how much extra fuel to carry and what it will cost to run the generator throughout the trip.

So, how much fuel does an RV generator use? In short, a 3500-watt RV inverter generator like the Champion 100573 will run about 17 hours on a 2.9-gallon gas tank at 25% load. In other words, 0.17 gallons (0.64 liters) of gas every hour or 4.08 gallons (15.4 liters) every 24 hours.

However, the fuel consumption of your generator will vary depending on a wide variety of factors.

In this post, we’ll take a look at the most common factors that determine an RV generator fuel consumption.

Some factors will help make your generator more fuel-efficient, whereas, others will help prevent it from reducing.

01. Reduce Electrical Load to Increase Fuel Efficiency

Load (electrical draw) is by far the #1 factor that determines how much fuel your generator drains in a given period.

It is determined by the number of RV appliances that are drawing power from your generator at any given time.

The closer your power draw is to the running wattage of your generator, the higher the load and vice versa.

For example, on a 3000-watt generator, running your 200 watt TV is a light load. Whereas, running your 2000 watt RV air conditioner is a heavy load.

Generally, the fuel efficiency of portable generators is advertised at a load of either 25% or 50%.

Try to avoid using all your appliances at the same time, especially the high draw appliances. Reducing the electric load on the generator will directly affect your fuel consumption rate.

Using your toaster, coffee maker, and your microwave simultaneously to prepare breakfast will heavily tax your generator. But, using one appliance at a time reduces the load and fuel use greatly.

Moreover, running a portable generator on full load for extended periods will not only increase fuel cost but also shorten its life.

Tip: Use LED lights and other energy-efficient appliances to cut down on power consumption.

02. Choosing the Right Size RV Generator

Choosing the right size generator for your RV will play an essential role in determining how much fuel your RV generator consumes per hour.

In general, there are two different types of RVs in terms of power use.

  1. 30 amp RV
  2. 50 amp RV

30 amp RVs are usually small, come with one air conditioner, and need less power overall. A 30 amp circuit can take in a maximum of 3600 watts of power at any given time.

Read More: How to choose the right size generator for your 30 amp RV?

On the other hand, 50 amp RVs are big, come with multiple air conditioners and other household appliances. A 50 amp circuit can take in a maximum of 12000 watts of power at any given time.

That is 3x more power compared to a 30 amp RV.

Read More: How to choose the right size generator for your 50 amp RV?

Getting an underpowered RV generator will not meet your needs. On the other hand, getting an overpowered RV generator means waste in terms of money, energy, and fuel.

For example, getting a 1000 watt generator with a 2000 watt power demand means running your generator on higher loads. Thus, increasing fuel consumption and reducing its working life.

On the other hand, getting a 5000-watt generator with a 2000 watt power need means you’re going to be wasting resources and money.

03. RV Generator Fuel Type

RV generators run on one of three types of fuel, i.e. propane, gasoline, and diesel. The fuel your generator runs on also determines how much fuel an RV generator uses.

This is because, some fuel burns quickly, whereas, some burn slow producing more energy.

Note: The fuel prices mentioned in this post are an average estimate and may vary with time.

Propane RV Generator

Propane is the most versatile type of fuel as it is easy to find, has a longer shelf life, and burns clean.

It is the most popular fuel type as RVs use it to run many appliances like refrigerators, furnaces, stoves, and generators.

However, in terms of fuel efficiency, it comes last and also produces less energy.

Propane costs anywhere between $3-$4 per pound and RVs come with multiple 10-20 pound tanks. You’re looking anywhere from $60-$80 per refill of a 20-pound propane tank.

A portable dual fuel generator like the Champion 100263 producing 2790 running watts will use about 1.4 pounds of propane every hour when run at 25% load. At this rate, a 20-pound propane tank will last you about 14.5 hours.

Gas RV Generator

Gas-powered RV generators are the most popular type of generators amongst RVers as these types of generators are easy to find on the market.

Gasoline is more fuel-efficient compared to propane but has the shortest shelf life compared to the three fuel types. Though you can extend its shelf life by adding a stabilizer like the  STA-BIL (22214) before storage.

Gasoline costs about $2.76 per gallon and a portable gas generator tank can hold between 1-10 gallons.

A portable gas generator like the Honda EU3000iS with a 3.4-gallon tank will keep your RV powered for about 19.6 hours at 25% load. At this rate, you’re looking to use about 0.173 gallons of fuel every hour.

Diesel RV Generator

When it comes to fuel efficiency, nothing can beat a diesel-powered RV generator. 

Diesel burns slow produces more energy and has longer shelf life compared to gasoline. Though, you can use an aftermarket diesel stabilizer like the STA-BIL (22254) to further extend its life.

However, diesel produces the highest pollutant and is difficult to find if you’re camping far away from a city. Moreover, portable diesel generators are way more expensive than the other two types.

Generally, motorhomes that come with a built-in or onboard generator are often diesel generators. They use the diesel from the RV fuel tank which removes the need to refuel your generator.

Diesel costs about $2.98 per gallon. A portable diesel generator like the Generac 6864 with a 12-gallon tank will cost you about $35.76 per refill. With this 5000 watt generator, you’re looking at about 32.4 hours of continuous power at 50% load.

04. Types of RV Generator

The type of RV generator you choose also plays a role in determining how much gas your RV generator uses per hour.

Generally, RVs use one of two different kinds of generators, onboard and portable.

Onboard RV Generator

Onboard RV generators are the ones that are built into your RV or motorhome. They use the same fuel type that is used to power your motorhome (gasoline or diesel).

Typically, built-in RV generators are powerful enough to power your entire rig. This may be a downside to some RVers who have low power demands to run a few small appliances and save on fuel.

However, it’s a great option for campers whose power demands meet the output rating of the onboard generator.

Portable RV Generator

A portable RV generator is a top choice for boondockers due to its portability, convenience, and ease of use. You can get a portable generator that either uses propane, gasoline, diesel, or dual fuel (gas and propane).

Depending on your power needs you can get a portable generator as small as 1000 watts to as powerful as 12000 watts. 

Moreover, you have the option to use two portable generators in parallel to increase the power output when the demand is high. Or use a single unit to power small appliances when power demands are low.

This can save you huge in terms of money, weight, and fuel.

There are three different types of portable generators:

  1. Conventional Generator
  2. Inverter Generator
  3. Battery Powered Generator

Conventional or open-framed generators come with a motor that runs at a constant speed irrespective of the load. Meaning, the generator will produce its rated wattage whether you need it or not.

Thus increasing fuel consumption.

Inverter generators, on the other hand, not only produce clean power that is safe for your sensitive electronics but also come with technology to reduce fuel consumption.

They use technology like an economy mode that determines the engine throttle depending on the load. Meaning, the generator produces more or less power depending on the electrical load, increasing fuel economy.

Battery-powered generators are what they sound like. They are your ideal candidate for powering small sensitive appliances like your laptop or cell phones or run a small fan.

They are also great for use inside your RV or tent as they produce ZERO exhaust gases and sound.

Read More: How to Quiet an RV Generator?

However, the downside to a battery-powered generator is, they need to be recharged which can be a time-consuming task.

Though, you can charge them in the car on your way to the campsite or use your RV solar panels to recharge them for free forever.

The MAXOAK BLUETTI EB150 is a great portable power station if you’re looking for an indoor generator.

Tip: Mount your portable generator on your RV to prevent it from being stolen and removing the need to carry it around.

05. Environmental Factors that Affect Fuel Efficiency

Every electrical appliance needs a certain condition to perform at its best and your RV generator is no exception. Any fluctuations in these conditions may lead to low efficiency resulting in high fuel consumption.

Here, we’ll briefly look at two different environmental factors that may lead to reduced fuel economy and performance.

High Altitude

As you climb above sea level, the lack of oxygen and pressures can hinder the proper functionality of everything including your generator. Without the right air pressure and density, your generator will produce less wattage while keeping the fuel intake high.

On the other hand, a reduction in the ambient air will impact the generator’s ability to dissipate heat. This will result in your generator overheating and further reducing performance.

Generally, a generator’s performance doesn’t vary much up to the 1000 meters above sea level mark. However, as you go higher, you’ll face a power reduction of about 3% per 500 meters of elevation.

Tip: If you often camp in high altitude areas, make sure you install a high altitude kit for your specific portable generator.

High Temperature

Like altitude, a rise in air temperature can seriously obstruct the optimal performance of any generator. 

The rise in air temperature reduces the quality of the air resulting in poor combustion. This results in a loss of power.

Additionally, with the ambient temperature above-recommended level, less heat is removed from the engine. This overheats the generator motor which can damage the generator and be dangerous.

Anything above 100 Fahrenheit for a considerable amount of time will have a detrimental effect on the performance and fuel economy.

Moreover, the power output will reduce by 3% with every 41 Fahrenheit increase in temperature.

Tip: Run your generator away from direct sunlight, under a shaded area (tree or RV awning), or use a generator tent running cover like the GenTent 10k to protect it from the sun, rain, and other elements.

06. Generator Age

The performance of any electronic appliance declines with age and your RV generator is no exception. With age, increases wear and tear resulting in reduced performance and fuel economy.

Typically, most generators are designed to provide anywhere between 1000-3000 hours of optimal performance. However, with proper use, care and maintenance, you can expect it to perform for decades.

07. Regular Generator Maintenance

Just like any other RV appliance, your RV generator needs regular maintenance. Proper maintenance will not only improve performance and fuel economy but will also add years to its life.

Generally, gas and diesel generators need higher maintenance compared to propane generators. However, keep in mind, no type of generator is maintenance-free.

Here are 6 generator maintenance tips that will help maintain high-level performance and efficiency.

1. Change the Oil

A regular oil change can ensure engine longevity while maintaining performance and efficiency. As the oil gets used up, its viscosity increases due to dust and other debris, forcing the engine to work harder.

The more the engine works hard, the more fuel it burns. Moreover, the longer you wait between oil changes, the higher will be the fuel consumption per hour.

But how often to change generator oil will depend on factors like:

  • How much the generator is used
  • At what load is the generator used
  • Is the operating environment dusty or clean
  • What brand of generator is it
  • The quality of the oil used
  • What is the operating temperature

Generally, a good rule of thumb is to change your generator oil and oil filter every 50-100 hours depending on the factors mentioned above. However, you should check the owner’s manual of your specific model to find out the recommended interval.

On the other hand, checking your oil level frequently (12 hours) will also give you a good idea about how broken down the oil is. Add oil if the level is low and change it if the color of the oil is deeper/darker.

Moreover, manufacturers recommend the first oil change of a brand new generator after 5-8 hours of use. This removes any foreign object that may have gotten in during the assembly process.

2. Check Air Filter

Every engine comes with an air filter that’s primary function is to remove solid particles from the air and prevent it from entering the engine.

A dirty or blocked air filter obstructs the flow of air resulting in an incomplete cycle of combustion. To compensate for the loss, the engine burns more fuel to attain the desired output.

This can result in a 5-10% increase in fuel consumption.

Generally, under normal circumstances, you are advised to change your generator air filter 2-3 times a year. However, if you boondock in areas with a lot of sand or dust like in a desert, you might have to change it more frequently.

Check your air filter once a month and dust it to remove dry dust. However, change the air filter if the dusting process doesn’t work.

3. Check the Spark Plug

A spark plug is a device that produces the spark to ignite the air-fuel mixture in the engine. A worn-out spark plug can seriously hinder your generator’s functionality while dropping your fuel economy by up to 30%.

A spark plug may underperform for a wide range of reasons but the most common is the accumulation of carbon.

Remove and inspect your spark plug once a month and clean any carbon or dirt deposits that may have formed.

4. Don’t Use Old Gas/Diesel

With every passing day, both diesel and gasoline lose their ability to produce the desired amount of energy. Meaning, if you run your generator with fuel that has been sitting in the tank for a while, it won’t burn efficiently.

Gasoline has the shortest shelf life compared to diesel.

So you either need to drain your fuel tank after your camping trip before safely storing your generator. Else, you need to add a fuel stabilizer to extend the working life of your generator fuel.

Use a gasoline stabilizer like the STA-BIL (22214) or a diesel stabilizer like the STA-BIL (22254).

However, you don’t have to worry about your fuel going stale if you use a propane generator.

5. Exercise your Generator Regularly

If you’re a full-time RVer you don’t have to worry about exercising your generator as you mostly run it every day. However, seasoned Rvers need to run their generators for 20-30 minutes every 30 days in storage.

This is called generator exercising which helps lubricate the moving parts, clean the carburetor and keep the generator battery charged.

However, the most important thing is, exercising your generator keeps it fit and in top working order.

Exercising your generator does not influence your fuel economy directly but is an essential part of the overall maintenance process.

6. Inspect the Exhaust System

The exhaust system in general is designed to reduce toxic emissions and noise from the engine. Moreover, an exhaust system has a critical role in the performance and fuel economy of the engine.

A generator with a broken or blocked exhaust pipe impacts the gas pressure inside. This will reduce performance while increasing fuel consumption.

Inspect your exhaust pipe for leaks and other damage regularly.

08. Break-In Correctly

A break-in is a controlled process of running an engine to optimize its moving parts for maximum performance. It also allows you to remove any loose metal shavings that came off from the first run with the oil drain.

Breaking in your generator properly can have a lot of benefits from performance to efficiency to longevity.

Follow the user manual of your specific generator to find out the recommended oil and how to break in a generator correctly.


Every generator is different. They have different output ratings thus different fuel efficiencies. One generator may be a fuel-efficient option for you and not for someone else.

The 8 factors we discussed above will surely help you maintain a constant fuel economy irrespective of the model you purchase.