Motorhome Generators–The Complete Guide

How Does a Motorhome Generator Work?

A Motorhome generator works by running its four functional parts operating in tandem: a fueled mechanical motor, the fuel supply system, an electric starter motor, and an electric power generator.  

Motorhome generators are powered by a fueled motor, usually a gasoline-powered motor. Most of these motors have two cylinders. Each cylinder is connected to a crankshaft, and has fuel, air, and exhaust ports. This design allows for continual firing and exhaust, which the crankshaft turns into combustion action. 

The maintenance of your generator’s motor is fairly simple:

  • Ensure that the motor is always well-lubricated with oil and always change the oil filter as scheduled. 
  • If you have a larger electric generator with a cooling system, check the coolant reservoir regularly to ensure the level is within indicated limits.
  • Adjust your antifreeze usage according to the weather. 

The second part of the generator is the fuel system. In this system, gasoline is mixed with oxygen in the carburetor and then injected into the motor’s cylinder. A spark causes the mixture to explode, moving the motor’s crankshaft. In a stand-alone generator, the fuel comes from its own fuel tank. That’s unlike in a built-in generator, where the gasoline comes from the motorhome’s main fuel tank.

The electric starter motor requires voltage to turn. Once it goes through several firing cycles, the starter is no longer needed, and the motor runs independently. 

Last but equally important is the electric power generator, the part of your motorhome generator that creates electricity. This occurs because a coil of wire wrapped around a shaft spins inside the opening of a larger coil of wire. The power generator shaft is attached to the shaft of the fueled mechanical motor, so both turn together.  

In general, you can check most of the parts of your motorhome generator on your own for basic maintenance and troubleshooting. You should keep a spare fuel filter in your motorhome, regularly check the air filter and wiring, and change the motor oil as needed. 

Do Class C Motorhomes Have Generators?

Most class C motorhomes have factory-installed generators that power the air conditioning, microwave, and TV. Most of these generators are gasoline-powered and use the same gas tank as the motorhome.

There is often a button near the side door or the driver’s seat that allows the driver to start the generator without getting out of the motorhome. This is especially helpful if you’re traveling in a hot area and want to turn on the air conditioning. 

The generator in a class C motorhome can also act like jumper cables if the engine battery is dead. To use it as such, turn on the generator, let it run, and then push the emergency start button while turning the key. This should start the engine. 

The fuel consumption of the generator in a Class C motorhome depends on the number of watts produced. In most cases, the amount of fuel used is relatively small. 

Do Class B Motorhomes Have Generators?

Most newer class B motorhomes have built-in generators. Whether a class B motorhome comes with a generator depends on the age and style of the RV. The size of the generator varies with brand, model, and size of the motorhome.

While most class B motorhomes have built-in generators, you may need to use a portable generator if your RV is an older or low-end model. Additionally, some class B motorhomes come with smaller generators, so you should check to ensure that the generator can efficiently power everything you need. 

Some class B motorhomes are smaller because they are built within the body of a traditional van. While this makes them easier to drive, it also means there is less space for everything you may need, including a generator. 

Need to purchase a portable generator for your Class B motorhome? I recommend the WEN Portable Inverter Generator from Amazon because it is less than fifty pounds and it runs quietly. It has most of the features you’d find in more expensive brands and models, but at a lower price. 

Do Class A Motorhomes Have Generators? 

Most new class A motorhomes have built-in generators that power the air conditioning and microwave. However, some brands and models, especially older ones, do not have a generator. 

Class A motorhomes are the biggest type of motorhome and are built on a commercial bus or truck chassis. Because of their size, you can really maximize your interior living space. Standard amenities in a class A motorhome include:

  • A full kitchen.
  • A dinette.
  • A full bathroom.
  • More than one sleeping space.
  • Ample storage space.
  • Entertainment systems.
  • LED lighting.

If you have an older model or are buying a class A motorhome used, it may not have a generator. You’ll need to get a portable one. For the ideal purchase, I recommend the Honda Portable Gas Power Generator on Amazon. This generator is powerful enough to operate all of the amenities class A RVs come with. It’s also extremely quiet, so you won’t bother your neighbors at the campsite.  

Can You Run the Generator While You Drive?

You can run your RV generator while you drive. It is safe to drive while running your RV generator. Doing so will not harm you, the generator, or the motorhome. 

However, one thing to keep in mind is that some states and cities have laws that prohibit propane use while driving. Most motorhome generators use gasoline, so this shouldn’t be a problem. But if your generator is propane-fueled, you’ll want to pay attention to local laws. 

Make sure that your gas tank is full so you get to your destination safely, keeping in mind that the generator draws gasoline from the same tank as the motorhome. Put otherwise, driving with the generator on will deplete your gas tank more quickly, so plan for more stops to refuel. 

Most generators have a safety feature that immediately shuts off the generator when the fuel tank drops below a quarter tank. This can be a handy feature, as it helps prevent you from running out of gas in the middle of nowhere. 

The ability to run your generator while driving your motorhome gives you the freedom to run the refrigerator, air conditioning, microwave, and TVs as you continue your journey. Passengers in the motorhome can keep themselves entertained with a movie (complete with microwave popcorn) as someone else drives.  

How Long Do Motorhome Generators Last?

Motorhome generators last for approximately 8-20 hours of continuous use, depending on the model. Built-in RV generators can safely run for days as long as you maintain them properly. 

The length of time you can run a motorhome generator depends on various factors, including wattage, how large the fuel tank is, and the type of fuel the generator uses. 

It is essential that you shut down your generator to give it ample time to cool off before refueling. That’s because gasoline fumes are flammable, and the heat of your generator could ignite a flame.

Depending on how frequently you use your generator and its maintenance, portable generators can last for 10,000 to 25,000 hours. Built-in generators last between 15,000 and 20,000 hours in their lifetime. To get the most use out of your generator, make sure you maintain it properly and change the oil filters regularly.

Generators can also suffer from a lack of use, so you should run yours for a minimum of two hours every month to prevent the fuel from breaking down, carbon buildup, and moisture buildup.  

Can You Run a Motorhome Generator at Night?

Motorhome generators can be run at night. Built-in RV generators and most portable generators can run all night to power everything within the motorhome without issues. It is safe as long as windows and doors are closed.

Ensure that if you’re running your motorhome generator at night, you keep the windows closed to prevent fumes and carbon monoxide from coming into your RV. Most generators come with a built-in sensor that will turn the generator off if it detects high levels of carbon monoxide, but it’s not a bad idea to get a carbon monoxide detector just in case. 

If you choose to buy one, consider the FIRST ALERT Carbon Monoxide Detector from It is battery operated and doesn’t require an outlet, which is perfect for an RV. Additionally, the 85-decibel alarm is sure to wake anyone up if, for some reason, the generator’s sensor fails and there is carbon monoxide present!   

How Much Gas Does a Motorhome Generator Burn per Hour?

A standard 5,000-watt gasoline generator consumes approximately one gallon of gasoline per hour. The exact amount of gas your motorhome generator will burn per hour will depend on your usage and the type of generator.

This usage varies depending on how often you’re using your generator and what you’re using it for. If you are running everything, like the air conditioning, refrigerator, microwave, coffee maker, and more, your generator will burn more gas than just keeping basic appliances running. 

It is good to know your generator and your usage and factor that gasoline usage into your trip planning. Your motorhome has a limited fuel tank, so having a grasp of your typical consumption is essential to know how often you’ll need to stop to refuel. 

An average 5,000-watt gasoline generator uses around 18 gallons of gasoline for a full day of usage. A 4,000-watt generator will use a little less gasoline, usually approximately three-quarters of a gallon per hour.

Ideally, you shouldn’t be running everything at all times. For example, if you don’t need to run your air conditioning, turning it off will help you burn less gas. 

How Much Do Motorhome Generators Cost To Replace?

Motorhome generators cost between $400 and $700 to replace. However, this range is merely an estimate. The cost of replacing your motorhome generator may vary depending on the type of generator you purchase.

The cost of a new generator depends on the brand, the power, and the fuel. There are many generators on the market, so you can get an inexpensive, no-name brand generator for $300 or less, but it may be worth the extra money to get a generator from a trustworthy brand, such as Generac, Energizer, or Winco. 

The wattage of the generator also influences the price. In general, the higher the wattage, the more the generator will cost. Generators that are 5,000 watts or more usually cost at least one thousand dollars, but most motorhomes don’t need a generator with that much wattage. 

For most motorhomes, a 3,000-4,000 watt generator will suffice. These generators cost approximately $700. 

There are a few ways to tell if your generator needs to be replaced. Here are some signs to look out for: 

  • Your generator is old, or you’ve used it for many hours. 
  • The generator uses more gasoline than it usually does, and isn’t running as efficiently as it should.
  • Your generator is slow to start. 
  • Your appliances in your RV aren’t functioning at full power, and brownouts are becoming more frequent.  
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