Whether you are renting an RV on Outdoorsy for the first time or purchasing an RV for travel or to rent out to others, it’s important to learn the basics of RV electrical systems. Read on for a basic understanding of your RV’s electrical systems, how they work, and what to be aware of in terms of safety. If you become an RV owner, long-term care and maintenance is a more complicated subject.
In this guide, we’ll cover:
Let’s get to it!
Understanding AC vs. DC
The majority of rigs have two electrical RV systems. There is an AC (alternating current) system that is similar to the one in a typical home. There is also a DC (direct current) system that works similarly to the one in a car. The AC system is powered by plugging your trailer into an external AC power source, while the DC system runs off one or more battery systems installed in your RV. Big appliances like the air conditioning, microwave, and power outlets, run off the AC power system. Your lights, water pump, fans, TV, and radio run off the DC power system. The AC system is capable of generating a lot more power than the DC system, which is limited by your RV batteries.
The two RV electrical systems are connected so that if you have AC power coming into your RV, it will charge up the batteries for the DC system. The device that does this is called a converter. Along with the RV power converter, many rigs also have an inverter, which is a device that turns DC power into AC power. RVs with an inverter will have specially marked wall outlets that run on the DC battery system but provide AC power.
Most RVs are set up so that if you have RV shore power (more about that later), you can run pretty much everything in the RV. If you don’t have shore power, then you are running off the DC system, which can run the essentials like the lights and water pump for a few days.
Here’s our fast tip:
Plugged into a power source = enjoy all the comforts of home
Running off a battery = use just the basics, and use them sparingly
Let’s take a quick look at each of the sources of power for an RV. Reference our RV electrical system schematic above as well.
Most RVs have one or more batteries. The batteries provide your RV with a source of power when no external power is available. The amount of power the batteries can provide on their own is fairly low — they can run the lights, water pump, and small appliances for the better part of the day, but that is about it. They can’t drive the air conditioning or heating systems either.
Your battery is charging any time an external power source is connected and providing power to your RV. Power sources include shore power, a generator, a vehicle engine, or a solar panel. When you are in motion, if you are plugged into a vehicle using the trailer adapter, the vehicle engine should charge your battery.
RV shore power is when you can plug your RV into an AC electrical grid. The available power you can draw on is measured in amps. The most common RV connections are 30 amps and 50 amps. You can connect your RV to a line running from someone’s house, but use caution. To charge an RV from a house, the RV would need to connect to the home system using either an adapter or the house would need a designated 30 or 50 amp connection.
Your RV will be set up to either use 50 amps or 30 amps depending on the size of the RV. You can connect your RV to a lower amp power source, but if you aren’t careful, it can be dangerous; you can damage the electrical systems if you try to draw more power than the shore power line is rated for. Typically, the worst that happens is you blow fuses, but you could damage the power source or your trailer.
When you connect to shore power at an RV park, there will be a circuit breaker on the pedestal. Remember to turn that on after you hook up to electricity, and turn it off when you disconnect to leave.
Generators work like RV shore power as they plug into your AC system and provide AC power. Typically, they don’t provide as much RV power as shore power does, but that really depends on the size of the generator.
Generators are rated in watts rather than amps. A 1000-watt generator is about right for a small RV or if you don’t need to run major systems like air conditioning. A 3500-watt generator is usually the next step up and can run most RV systems on most RVs.
Overdrawing a generator is not as risky as overdrawing shore power. If you try to overdraw a generator, you simply won’t get enough power to make everything run properly. Overloading your generator might damage some appliances, though it is not likely.
Some motorhomes have a built-in generator, which is separate from the main engine and usually located in an outside bay. These can be especially handy as they are insulated and thus not very noisy.
External generators are prohibited during quiet hours, especially at night. The most important safety rule for external generators is never to use them indoors since they produce a lot of carbon monoxide gas, and it can become fatal very quickly in an enclosed space.
Note: If you must use an external generator, you should never operate the generator indoors since carbon monoxide gas can build up in enclosed spaces.
Solar and wind
The important thing to understand about renewable energy sources is that they are designed to charge your battery, not to provide you with on-demand power.
They generate DC current rather than the AC power you get from shore power and generators. Thus, you are still limited by the amount of power your battery can provide, but you can keep using it far longer since you can recharge it over time. Solar power gives you a renewable source of power off-the-grid, which is perfect for boondocking adventures.
The advantage of solar power is that when there is sun, your batteries are constantly being charged; the disadvantage is that you can’t run anything more demanding than you could normally run off the battery system alone.
Typically that rules out the air conditioning system, electric heaters, the microwave, and other high-draw appliances.
Just like your house and car, RVs have fuses that help protect the RV electrical system from overdrawing or power surges. If you lose power somewhere in your RV, chances are a fuse has blown somewhere.
Chances are also good it blew because you were trying to draw too much power at once. You should make sure you know where the fuse panel is before taking out an RV.
Most RVs will have resettable fuses like those in your house; others may have fuses you must replace like those commonly found in cars. If you have the replaceable kind, it’s a good idea to keep a few spares on hand in case you blow a fuse.
Propane vs. Electricity
Your RV may have some appliances that can either run on electricity or propane. Heaters, water heaters, and refrigerators that can switch between the two are common.
The rule of thumb with these is that if you are connected to RV shore power, you should use the electricity option — or a hybrid electric and propane option if your rig comes with a hybrid system.
If you are boondocking —or camping off the grid — use the propane option. It really comes down to what you have more of and what operates your system best — propane or electricity.
Some RVs have a built-in surge protector, and some have none at all, so you will have to buy an external portable surge protector.
The purpose of using a surge protector is to make sure the RV shore power is clean and steady before letting the electricity into the trailer; the surge protector acts as a guard from power surges both natural and unnatural.
Surge protectors are not essential, but they do help preserve the integrity of the RV’s electrical systems.
If you use a surge protector, be aware that there is usually a short delay from when you connect power to when the surge protector allows power to the RV. Typically it is around 20 to 60 seconds. This delay can be confusing if you are not aware of it.
Before you go
Generally, operating an RV electrical system is a no-hassle situation, but it is important to know the basics so you can have a trouble-free adventure. If you want to learn more about basic RV electrical systems, check out Learning Your Way Around an RV. If you want to dig a little deeper into electricity, you can read more about it here.
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