How Do RV Generators Work (Gas, Diesel, Propane and Solar)


Generators are the lifeblood of your RV. They provide energy to any appliance that requires an outlet to run, and pumps powerful energy to large appliances like air conditioners and hair dryers.

You’re going to want a generator.

So, what is a generator, how do they work, and what comforts can they provide for RV campers?

First, a RV generator is a machine that creates electricity in the form of AC (Alternating Current). To learn the difference between AC and DC current, read more here.

RV generators provide high power electric access, and make it possible to run energy-hungry appliances that require an outlet.

What is considered  an “energy-hungry” appliance?

Simple: Any appliance that requires an AC outlet to run needs more energy than your RV’s house batteries can provide on their own.

Some appliances in your RV will run off of DC (Direct Current), and use little energy. These include: Water pump, water heater, in-built ceiling fans, and RV lights.

Without a generator or shore power hook ups (ie plugging into “the grid”), RVing is still possible and you’ll have access to the aforementioned low-energy usage appliances for a few days or weeks before needing to recharge your RV’s house batteries.

But if you want to live or camp in your RV “off grid” while maintaining access to creature comforts like an electric coffee maker or hair dryer, you’ll need to use a generator.

The following chart will give you an idea of just how much energy these generator-dependent appliances actually use.

These are watt / amp averages of common RV appliances with the chart meant only as a guide; In order to determine your energy needs, make sure to look at the watts and amps on each appliance you intend to use in your RV.

By performing your own calculations of watt / amp requirements, you can ensure you have the right generator size to fit your personal needs, and will avoid overloading your system.

How to Calculate Your Needs
Watts ÷ Volts = Amps
Amps x Volts = Watts
Appliance Load Range (Watts) Avg. Load (Watts) Amps
Air Conditioner 1400 – 2000 1700 14
Coffee Maker (Keurig) 200 – 1500 200 -400 9.5 – 20.5
Hair Dryer 800 – 1800 1000 15
Microwave 650 – 1000 1000 7.5 – 13
Refrigerator 600 – 800 800 2 – 8
Water Heater 1000 – 1500 1250 9 -13

Types of RV Generators

There are four commonly used types of generators for RVs: Gas, Diesel, Propane and Solar.

Gas Generators

RVs are typically equipped with a gas generator already installed. These generators share the fuel from the RV’s fuel tank. When the gas in your fuel tank drops below 1/4 full, your generator has a “fail-safe” and will stop working until you fill up with more gas.

This ensures that you don’t accidentally use up all your RV’s fuel and find yourself stuck in the middle of nowhere!

If your generator stops working after using it for a prolonged time, check how much fuel your RV has. If it’s low, you’ll know it’s time to find a gas station asap.

Gasoline is a convenient energy source for RV generators as it’s so easy to find at any gas station.

One of the most popular gas generators found in RVs is the Cummins Onan generator (Amazon). Our own 1992 Cobra Passport RV came with an Onan already installed, and has run great for over 7 years.

Diesel Generators

Diesel generators are very similar to their gas counterparts. The main differences being: Diesel generators are less commonly found pre-installed in RVs, although diesel is a more efficient fuel than regular gas.

The fuel efficiency you’ll get from using diesel means you’ll make less trips to the gas station, and you’ll be able to run appliances for a longer amount of time while on the road.

So, not only are diesel generators efficient, they may also save you a bit of money.

Propane (Liquid) Generators

Liquid propane generators are not commonly found in RVs, although they are certainly an option.

Propane burns cleaner than both gas or diesel fuel, so if you’re looking for a more environmentally-friendly generator to power your appliances, this might be a good fit for you.

However, refilling this type of fuel may prove more difficult as you’re reliant on gas and dump stations for refills. Not all stations will have liquid propane, and this may leave you in tough spot unable to use your appliances until you can find a station with the right fuel for your generator.

Propane is also much weaker than either gas or diesel- providing 10% less power than gas/diesel fuel- meaning you’ll get a lot less bang for your buck when it comes to using this type of generator. And unlike a diesel generator, you’ll likely pay more in the long run to power your appliances this way.

If a propane generator still seems to fit your needs, but you want a bit more versatility, hybrid generators that run off both propane and gas are also sold. You can check out various options here (Amazon).

Solar Generators

Solar generators are popular for “van lifers”, as they are small, don’t require gasoline, and simply require energy from the sun to run.

A more accurate name for these would be a power station, because they don’t actually generate power like gas/diesel generators; Solar power stations can merely store energy from the sun for later use.

A solar generator comes in two parts: the battery, and the solar panels themselves.

Solar generators, like the Jackery portable solar generator, are compact, easy to set up, and can run/charge many appliances like a laptop, TV, gaming some gaming consoles, and charge phones.

However, solar generators come with a number of downsides. Perhaps most important to know is that solar generators are very limited in the power they can provide.

They cannot run the big energy-sucking appliances like a microwave, air conditioner, large plug-in fan, hair dryer, coffee maker…

All of these require too much energy for a “generator” like the Jackery to run.

If the Jackery portable power station is over-run and cannot power an appliance, it will automatically shut off.

In addition to energy output limitations, solar power stations are also fully dependent on the sun to store energy (if you’re on the road/off grid).

They can be plugged into an outlet to charge, but you’ll need to plug into shore power in order to do so. Otherwise, cross your fingers for sunny days ahead!

But, if a solar generator is so limited, why use one?

Solar generators remain a popular option for RVers due to their ease of use, portability, functionality, and they’re a great backup option to have on-hand in case your gas/diesel generator has an unexpected problem arise.

Not all RVers want larger appliances like microwaves, hair dryers, electric coffee makers, and the like in their vehicle. Instead, some nomads find it less of a hassle to live without these appliances and prefer to power just the basics: Laptops, phones, tablets, and cameras.

RVers and campers who prefer to live with just the basics, a solar power station like the Jackery will fit that lifestyle well, providing the necessary amount of energy.

Generator Maintenance

For generators that run off of fuel (gas/diesel), maintaining the integrity of the machine is a must.

The most neglected aspect of maintenance is “exercising” the generator.

“Exercising” a generator means running it for a few hours every month, in order to maintain its functionality.

If a generator is not exercised enough, a number of problems can result.

Problem #1  Fuel that sits in a generator without running, results in the fuel breaking down and gums up the system. This can lead to power surges when you eventually do try to run the generator.

Problem #2  A built up of moisture occurs if a generator is left sitting without use. When you run a generator, the machine will heat up, getting rid of any moisture inside. However, if it’s never “exercised”, moisture will build up and require repairs.

Now, I’ll be the first to admit that I’ve ignored exercising my own generator. And when I leave it for over a month, the next time I do, the lack of care is obvious…

Luckily, our generator still works, however, when we run it after a time of neglect, it runs loudly, and runs dirty. It takes about 30 minutes for the generator to quiet down, have an even sound, and to emit less exhaust.

Fuel Preservatives

If you plan on not using your generator often, or know it’ll be in storage for more than a couple months, you might want to add a fuel preservative to avoid big problems.

Fuel, if left in a tank for an extended time, go stale. When gas begins to break down, that’s when problems can start to arise.

Preservatives can be added to your RV’s fuel in order to maintain the integrity of the gas in your system for longer.

Exercising your generator and checking/replacing the oil is still essential, but the addition of fuel preservatives (Amazon) can buy you a little time before the fuel starts to degrade.

Size of Generators: Which is the Best?

After you’ve determined what kind of generator you want, and you know how to properly maintain it, now you need to decide which size generator is right for you.

The size of a generator refers to the load it can power. In order to calculate the right size for your RV, you’ll need to look at each appliance you plan on using (that require AC power), and determine how many watts they require to run.

Each appliance from your laptop, hand vacuum, to your air conditioning unit and coffee maker, will have a sticker. On this sticker, you should be provided with the device’s energy-use stats, given in Watts (W), Amps, or milliwatts (mW).

Add together how many watts using all these appliances will require.

Important to note: Appliances like an RV air conditioner, initially have a higher “surge” of power when first turned on. That means that it requires an even larger amount of energy in order to get up and running.

After a few minutes, the appliance will begin to even out and run on less energy.

Make sure you take into account any appliance, like an air conditioner, that will require more Watts to start running. This is important when you’re determining your energy needs to decide on the right size generator for you.

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