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What size generator do I need for my RV?

What size generator do I need for my RV?

One of the advantages and reasons why people enjoy recreational vehicles is their autonomy, they can provide you with the comforts of a regular dwelling even in the middle of nowhere.

To do so, they still need a source of power, so you might wonder what size generator I need for my RV.

In most cases, you will need a generator that can provide you with slightly more power than your RV consumes. Though, in one case you can get away with practically any size of generator.

The exact size depends on the way you are planning to use it, but also the specifications of your RV. So, let’s get into details of how generators can be used, and how to calculate what size you need.

What size generator do I need for my RV?

As I’ve said above, a generator should have more power than the RV needs, in most cases though there is an exception when it can be practically any size.

But first, you need to understand what is the size of a generator, as they come in many sizes. It is not its physical dimensions, though generators come in various shapes and dimensions.

When you hear or read about generator sizes, it is about its power output. While its dimensions do decide your choice, how much power it can produce is much more important.

And the importance is best seen in the case that it is too small. If its dimensions are smaller than the available space for it, there are no issues. But not enough power can be a problem.

So, how big a generator do you need for an RV? It should be able to produce more power than you need, but there are certain factors that decide how much power you need, so let’s talk about them.

Factors that decide the needed size of the generator

Not all RVs are equal, nor either are the needs and desires of all RV owners.

So, the first factor that decides the required size of the generator is how it will be used. There are two scenarios:

  • recharging house batteries,
  • powering the RV.

In the first case, the power output of the generator needs to be high enough to charge the batteries, but in the second one, it depends on the current rating of your RV. It can be:

  • 30 amps,
  • 50 amps.

If you want to use your power generator for powering all appliances in your RV, instead of drawing power from house batteries it is important that you know how to calculate the maximum power draw of your RV, which we will cover later in this article.

RV generator size for recharging house batteries

When it comes to just charging your RV batteries, practically any size of it is big enough. One thing you should have in mind is that the charging times depend on the capacity of the battery pack, not the power output of the generator.

RV house batteries are the 12V type, which means that they are typically charged with 14.4V or 15V power. The standard converters on recreational vehicles will use either 20amps or 30amps to do it.

So, the generator power output that is needed for charging house batteries can be calculated by multiplying these numbers.

An absolute minimum would be 14.4V at 20amps, which is 288 watts, and the highest common power draw is 15V at 30 amps, which is 450 watts.

Power generators are rated in watts, and for all intents and purposes, the lowest rated RV generators available on the market are 600 watts.

Under 600W rated generators you can find only the small portable ones that do not have an appropriate power outlet to be connected to an RV. So, for all intents and purposes, all available RV generators are more than powerful enough.

Generator size for 30 amps RVs

If you are planning to completely run your RV off of a generator, then you should do a bit of calculation of how much power your RV might be using.

So, let’s do it for an RV that has a 30 amps system. You could go around your RV and measure the maximum draw of all 120V appliances, but that is impractical.

Instead, when you multiply the maximum power draw, 30 amps, and 120V you get the maximum designed power draw, which is 3,600 watts, or 3,6kWh.

If your RV uses a 30 amps system, this is the absolute maximum draw, though your actual maximum power could be lower, depending on the number of electric devices. So, any generator with equal or higher power is good.

Generator size for 50 amps RVs

For the 50 amps RVs the calculation is similar to the calculation for 30 amps ones. But, there is one critical difference.

The 30 amps RVs have one main 30 amps circuit, while 50 amps RVs have two main circuits. So, in this case, you have to multiply the voltage by double the maximum amps rating.

In other words, for these RVs, the maximum designed power draw is 12,000W, so a 12kWh power generator will be able to supply it with power when it has the maximum possible electrical appliances, and they are all turned on.

Your actual power draw will be lower, most often between 6kWh and 9kWh, but for that, you must find the actual power draws of your appliances.

When calculating the real power needs of your RV, you have to sum up the maximum power ratings of your appliances, in the case of those with electric motors, such as ACs and fridges, you need to use the starting current power draw.

Types of generators

Not all generators are made equal, and the most important division between them is based on which fuel they use. Power generators use an internal combustion engine, so you would be correct to presume that there are the same types as car engines. There are five types:

  • LPG or propane,
  • butane-powered,
  • gasoline-powered,
  • diesel-powered,
  • FlexFuel-powered, which can run on pure gasoline, E85, and everything in between.



RVs are often called “homes away from home”, and to serve that purpose they need to have power supplied either by the shore connection or a power generator. Which will lead you to ask what size generator I need for my RV.

If you need it just for charging the house batteries, any RV generator available on market is powerful enough. But if you wish to power your RV appliances with the generator a 3.6kWh generator will be enough for a 30 amps RV, and 12kWh for a 50 amps rate.


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