What is an RV Inverter and Do I Need One?

When you start delving into the world of RV electrical systems, you’ll quickly come across the term “inverter.” It sounds technical, but its function is pretty straightforward and can significantly enhance your RVing experience, especially if you enjoy camping off-grid (boondocking).

As an RVer who values the freedom to camp anywhere, I can tell you that an inverter is a game-changer for many. Today, I want to explain what an RV inverter does, the different types, and help you decide if you need one.

An inverter converts 12V DC battery power to 120V AC power, allowing you to use household appliances when not plugged into shore power. It’s essential for boondockers who want to use things like coffee makers, microwaves, or TVs. This is a perfect, concise explanation.

Understanding the Basics: DC vs. AC Power in Your RV

Your RV has two main electrical systems:

• 12-Volt DC System: This system runs off your house batteries. It powers things like your interior lights, water pump, furnace fan, vent fans, RV refrigerator (when on propane mode, the control panel is still 12V), and usually your slide-out motors and leveling jacks.
• 120-Volt AC System: This system powers your household-style outlets, air conditioner(s), microwave, residential-style refrigerator (if equipped), and often your TV. It works when you are plugged into shore power at a campground or when you’re running your RV’s generator.

What Does an RV Inverter Do?

An inverter “inverts” power. Specifically, it takes the 12-volt Direct Current (DC) power stored in your house batteries and transforms it into 120-volt Alternating Current (AC) power.

This means that with an inverter, you can use many of your 120V AC appliances and outlets even when you are not connected to shore power or running a generator, by drawing power from your batteries.

It’s important to distinguish an inverter from a converter. A converter does the opposite: it takes 120V AC power (from shore power or a generator) and converts it to 12V DC power to run your DC appliances and, crucially, to charge your house batteries. Most RVs come standard with a converter.

Many modern RVs, especially larger ones or those designed for off-grid use, come with a combination Inverter/Charger. This single unit can both charge your batteries when on AC power and invert battery power to AC when needed.

Types of RV Inverters

There are two main types of inverters based on the quality of the AC power they produce:

Modified Sine Wave (MSW) Inverters

• These are generally less expensive.
• They produce an AC waveform that is a stepped approximation of a pure sine wave. While they can run many simpler appliances (like resistive loads such as a basic coffee maker or incandescent lights), they can cause problems with more sensitive electronics. Some appliances might buzz, run hotter, or not work at all. Sensitive electronics like laptops, some medical equipment (like CPAP machines), variable speed tools, and some modern TVs might be damaged or malfunction with an MSW inverter.

Pure Sine Wave (PSW) Inverters

Product Example: Go Power GP-5000HD Heavy-Duty Modified Sine Wave Inverter

• These are more expensive but produce a clean, smooth AC waveform that is the same as or better than the power you get from your home outlets (or shore power).
• Pure sine wave inverters are compatible with virtually all AC appliances and electronics, including sensitive ones. For this reason, PSW inverters are highly recommended for most RV applications, especially if you plan to run computers, TVs, medical devices, or anything with a sophisticated electronic control.

Do You Need an Inverter?

Whether you need an inverter depends on your RVing style:

• If you primarily camp in full-hookup campgrounds: You might not need an inverter, as you’ll always have 120V AC power available from the shore power pedestal.
• If you enjoy boondocking or camping off-grid: An inverter can be invaluable. It allows you to use essential or convenient AC appliances without having to run a noisy generator all the time. Think about making coffee in the morning, using a microwave for a quick meal, watching TV, or charging your laptop – an inverter makes these possible using your battery bank.
• If you want to use specific AC appliances on the road (while driving, for motorhomes): An inverter can power these items while you’re traveling.

Sizing Your Inverter

Inverters are rated in watts. This rating indicates how much continuous power they can supply. You need to choose an inverter size based on the total wattage of the AC appliances you want to run simultaneously.

1. List the Appliances: Make a list of all the 120V AC devices you might want to use at the same time.
2. Find Their Wattage: The wattage is usually printed on the appliance’s label. If it only lists amps, you can calculate watts: Watts = Volts x Amps (use 120V for the voltage).
3. Consider Surge Wattage: Many appliances (especially those with motors, like microwaves or refrigerators) require a higher surge of power to start up than they do to run continuously. Inverters also have a surge rating (or peak power rating), which they can supply for a short period. Ensure the inverter’s surge capacity can handle the startup demand of your largest appliance.
4. Add a Buffer: It’s a good idea to choose an inverter with a continuous wattage rating that is about 20-25% higher than your calculated maximum simultaneous load to provide a safety margin.

Common inverter sizes for RVs range from a small 300-watt unit (good for charging laptops or running a small TV) to 2000-3000 watts (capable of running a microwave, coffee maker, and other moderate loads). Running an air conditioner off an inverter is possible but requires a very large inverter and a substantial battery bank, often lithium.

Battery Considerations

Remember, an inverter doesn’t create power; it converts it from your batteries. Running high-wattage AC appliances through an inverter will draw a significant amount of power from your 12V battery bank.

• Battery Capacity: You need a sufficiently large house battery bank (measured in Amp-hours, Ah) to support your inverter usage. Lead-acid batteries (flooded, AGM, Gel) can typically only be discharged to about 50% of their rated capacity without damage. Lithium batteries (LiFePO4) can be discharged much deeper (80-100%) and handle high current draws better, making them ideal for inverter use.
• Battery Type: Lithium batteries are superior for inverter applications due to their depth of discharge, high current capability, and longer lifespan, but they are more expensive upfront.
• Charging System: You’ll also need a way to recharge your batteries (solar panels, generator, or shore power via your converter/charger).

Final Thoughts

An RV inverter can significantly enhance your off-grid comfort and convenience by allowing you to use your favorite 120V AC appliances powered by your batteries. If you enjoy the freedom of boondocking or simply want the ability to use certain devices without relying on shore power or a generator, a pure sine wave inverter, appropriately sized for your needs and paired with an adequate battery bank, is a fantastic upgrade.

Consider your power needs, your RVing style, and your budget. For many, including myself, the ability to brew a fresh cup of coffee or watch a movie in a remote, beautiful location, all powered silently by the sun (via solar and batteries) and an inverter, is what RVing freedom is all about!

I’m Bill Rowell, the founder of RVupgrades.com. In 2002, I launched the business to help fellow RV enthusiasts find unique and hard-to-find products. Over the years, it’s grown to offer more than 15,000 items, with a warehouse in Eastlake, Ohio. Having owned and repaired nearly every type of RV, I bring over two decades of hands-on experience to the table. For me, this isn’t just a business – it’s a passion and a way of life that I love sharing with the RV community.

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