RV Electrical Power Systems

The RV Beginner's Guide to Powering an RV Electrical System

(With Diagrams)

You probably chose your RV at least in part for its touches of comfort and luxury—there's a reason you chose a trailer or motorhome over camping in a tent, after all! But enjoying amenities like television, microwaves, etc. isn't quite as straightforward in an RV as in a house. There's a bit more to it than walking in and pressing a button!

Maybe you've heard that RVs run on both 120V AC and 12V DC power (or maybe this is news to you—in which case, that's fine, we'll go over all that below!). Maybe you're not sure what this means or how an RV electrical system actually works. Does your RV need to be plugged in? Can it run off batteries? Do you need a generator? To make the most out of your rig's capabilities and understand what limitations you have, it's important to understand how your electrical system functions.

We'll break it all down for you below (don't worry, you don't have to be an electrician to understand it!). Then we'll help you figure out what you'll need to camp the way you've always dreamed of.

How Does an RV Get Power?

Firstly, it's important to understand that your RV actually operates using several separate electrical systems. A trailer that you tow will have 2 systems—a 12V DC system (like what your vehicle uses) and a 120V AC system (what everything in your sticks-and-bricks house runs off of). Together, they make up your "house" system, which controls all the amenities inside your RV's living space. A motorhome that you drive will have these two systems as well as a third system, a 12V DC coach battery. This third system has nothing to do with running your appliances, just driving, so we'll focus on the house electrical system in this article.

There are whole books written on AC and DC currents and how they work, but it really boils down to this: your RV's DC appliances include most of your basics such as your lights, fans, water pump, slide outs, etc. AC appliances typically include larger "household-y" items like the microwave, refrigerator, and air conditioner. DC power comes from your batteries (or external DC sources that feed your batteries, like solar power), while AC power comes from external AC sources, like shore power or a generator.

However, keep in mind that these electrical systems CAN overlap. That is, you change AC power into DC power and vice versa. The devices that do this are called a converter and an inverter. Most RVs come with a converter, and some come with an inverter these days as well. However, both can be upgraded or purchased separately.

Converter: Typically built in. Converts incoming AC power to DC power to charge your battery bank (not necessary to run DC appliances).

Inverter: May be included or purchased separately. Inverts DC power to AC power so you can use AC appliances when not plugged into shore power.

Running DC Appliances

Again, when you think of your RV's DC power, just remember that all your DC appliances are powered directly from your battery bank. This means you can use these amenities anywhere as long as your batteries are charged (and they should always be charged—letting your charge drop below 50% will shorten the lifespan of your batteries!). Since DC power comes from your batteries, you're limited to powering what your battery bank can handle.

So how exactly do you charge your batteries and power your DC appliances? There are two main ways to do it:

Directly charge your DC batteries with a DC charger, alternator, or solar panel
Use built-in converter charger to change AC power into DC power and feed your batteries

For an in-depth look at charging an RV battery, check out our article here.

Running AC Appliances

Unlike DC power, your AC appliances are NOT powered directly from your batteries. This means there are two ways to get AC power in your RV:

Plug into an external AC power source (shore power or generator). You can run your AC appliances directly from this power source.
Use an inverter to change your 12V DC battery's power to 120V AC and power your appliances

Many big-ticket AC appliances, such as refrigerators, have both an electrical and propane mode. If you have access to electrical hookups, such as at a campground, you'll want to take advantage of this and use the electrical mode. If you're boondocking (camping off-grid), switch to propane to spare the drain on your electrical system.

What's the Best Way to Power an RV?

Now that we've gone over how the electrical systems in your RV work and how to power them, let's talk about how your RV's power capabilities relate to your trip, specifically. There are 3 main scenarios you'll run into when RVing:

Staying at a campground
Boondocking (camping off grid)
Storing your rig

You'll need to power your electrical system differently depending on which scenario you're looking at and what you have available. We'll go over each of these scenarios below.

Scenario 1: Camping with electrical hookups (shore power)

Let's start here, with the easiest way to camp. If you're staying at a campground, you'll typically have access to a power pedestal. Power pedestals typically provide a 30-amp outlet (and often a 50-amp outlet) for your RV power cord. Just plug the RV end into your power inlet, plug the pedestal end into the provided outlet, and you've got power!

The main thing to remember at the campground is that an RV with 30-amp service should plug into a 30-amp outlet, and an RV with 50-amp service should plug into a 50-amp outlet, or else you'll need an adapter. For a closer look at how 30-amp and 50-amp service works, check out our guide here.

Using AC Power

If you have access to electrical hookups, use them. This is the easiest, most efficient way to power your AC appliances!

Using DC Power

Using DC appliances at a campground is pretty simple, too. When you plug in to shore power, some of that AC power will automatically be directed to your converter, which will feed back into your DC batteries.

Additional recommended products:

(We highly recommend picking these up for campground use!)

Scenario 2: Boondocking (Camping Off Grid)

Going off grid and away from campgrounds can be a freeing, rewarding experience. However, it also means you have to get creative with powering your RV, since you won't have the benefit of electrical hookups.

Using AC Power

The easiest and most efficient way to get AC power without an electrical hookup is by using a generator to directly power your AC appliances.

However, if you don't love the idea of relying solely on a generator (either because they're noisy, they emit fumes, or their use is limited in your camp environment), the only way to use AC power is to use an inverter to "borrow" power from your DC batteries and change it to AC.

However, this means you have to be on top of keeping your DC batteries sufficiently charged so there's enough power there to "borrow." You'll have to be a lot more conservative with your power use, particularly when it comes to power-hungry appliances like your air conditioner.

Using DC Power

You can use DC power anywhere as long as you keep your batteries charged. There are three main ways to do this:

Solar power: Solar panels supply DC power directly to your batteries.
Generator: Your built-in converter changes the generator's AC power into DC for your batteries.
Battery Charger: A DC battery charger like the Manager30 or BCDC by Redarc uses solar power as well as your tow vehicle/motorhome alternator to charge your batteries.

Additional resources:

Scenario 3: Storing Your RV

When it's time to call it for the season and store your RV until spring, you'll want to make sure your battery doesn't go dead in your absence. There are essentially 2 ways to do this:

AC to DC ChargerIf you have access to AC power (like a standard wall outlet), the easiest way to keep your battery juiced up is with one of these chargers. They plug directly into the outlet, change the AC power to DC power, and charge up your batteries. (Note: if you need a charger both for storage and for boondocking, the Manager30 is an excellent all-in-one device.)
Solar battery box or solar chargerThese options are ideal if you'll be storing your battery outdoors. Many battery boxes even come with built-in locks to keep your battery secure until you get back to it.

Additional resources:

How to Winterize and De-Winterize Your RV

30-Amp and 50-Amp RV Service: 7 Things You Need to Know

The Best RV Battery Chargers

How Much Solar Power Do I Need for My RV?

Related Products

Shop Generators

Shop Solar Panels

Shop Inverters

Written by: Amber S.

Updated: 6/18/20

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