Are you setting up your RV with batteries for off-grid power? If so, congratulations! Off-grid power is a fantastic way to increase your freedom on the road and allow you to stay off the grid comfortably. One critical piece of your system will need to be the correct inverter. Because of this, you’ll need to know what size inverter you need for your RV. 

Below, we discuss what an inverter is, how to estimate your power needs, and how to choose the right one for you. Let’s begin. 

What Is an RV Inverter?

To explain what an RV inverter is, we must first discuss the different types of power in your RV. Most electrical devices run on AC power at 120 or 230 volts, like what you find in your home. This is the type of electricity received from the mainstream electrical grid, and it’s, therefore, the power your RV receives when you plug it into shore power. This is why you don’t need an inverter when you connect to the grid. 

Your batteries, however, run at 12V DC power. This runs most of the lights and appliances in the RV that keep operating when you unplug. However, it does not run higher power appliances, thus, in order to power electronics such as your microwave, coffee maker, laptop, etc., you’ll need to convert the DC power to AC power.

How do you do this? With an RV inverter!

How to Choose the Right Size Inverter for Your RV

Inverters come in a wide range of sizes with varying abilities. Choosing the right size inverter for your RV will depend on several factors. Let’s explore the questions you should ask before making your purchase. 

What Are You Trying to Power?

First and foremost, you’ll need to determine which devices and appliances you want to power at the same time. This will help you decide which size inverter you’ll actually need. Begin by making a list of the electronics in your RV and adding up the watts they require. You’ll want to factor in both the running watts and the surge requirements, as some appliances (like microwaves and refrigerators) have high surges when they first startup. 

Once you’ve added up the number of watts you’ll need to power (including the surges), add 20%. This will tell you the minimum size inverter you’ll need to power your devices. When looking at inverters consider that they frequently have surge capacities that they can endure for short times.

What Is Your Battery Bank Capacity and Type?

Matching your inverter to your battery capacity and type is very important. An inverter that is too big for the battery bank will drain it quickly and the batteries may not be able to power it appropriately. While there is no set requirement for size, the following is a general rule of thumb recommendation when operating with our Battle Born Lithium batteries. We recommend having a minimum of 100Ah battery for each 1000watts inverter capacity. For example, a 3000-watt inverter would need at least three 100Ah Battle Born Batteries.

Just as important as the capacity is the battery type. Lead-acid batteries have a high Peukert exponent that causes them to lose significant capacity when large loads are applied. Because of this, utilizing a larger inverter with a lead-acid battery bank requires an oversized system to limit this effect. For example, it’s recommended to have at least 800Ah of battery capacity in lead-acid to operate a 3000-watt inverter, whereas with our lithium, 300 Ah will work.

What Is Your Biggest Power Draw?

Keep in mind that you do not need to be able to run everything off your inverter. However, it’s a good idea to understand your largest loads and how often you will be running them.

If you only have a 2000-watt inverter, you may need to turn things off before running a microwave. If you don’t want to worry about this, look at your large loads and oversize the inverter so that you have capacity.

How to Estimate Your RV Power Needs

Most inverters will range between 1,000 watts and 5,000 watts, and you’ll probably need an inverter size somewhere in the middle. Many wonder what size inverter they need for their RV and estimate something far larger than necessary.

You can easily estimate the size inverter you’ll need by adding up the largest number of watts you’ll be using at a given time and adding 20%. For example, let’s say you need 1,500 watts to run your computer and microwave at the same time. Take 1,500 + 300 (which is 20% of 1,500) = 1,800 watts. This means you’ll need a pretty average size inverter of at least 2,000 watts. A 2000- or 3000-watt unit is the most common size used in RVs.

Does the Inverter Need to Power the Whole RV?

Thankfully, no. If this were the case, we would all have to purchase very powerful inverters. If you’re frequently camping off-grid and boondocking you may want your entire RV on the inverter to power every outlet in the camper. However, for shorter periods of time or only to have a couple of outlets powered, you can wire in an inverter to just handle those draws.

You always have the choice to hook your inverter to a subpanel in your RV. This means you may only have two or three receptacles that can power devices, and for many of us, that’s all we need! In this case, you’ll just need to ensure your inverter can power the devices that will be plugged into that subpanel.

Are There Drawbacks to Larger Inverters?

Inverters use power just to be on, and the larger the inverter the more power it will draw at idle. Inverters also operate most efficiently with larger loads on them, thus, large inverters will be less efficient and waste more power if used only for light loads. Because of this, it is not recommended to oversize an inverter unless the power needs require it.

Can an Inverter Power a Whole RV?

Do you have an epic solar and battery setup and want to power your entire RV? Luckily, some inverters can do that. In this case, we recommend a hybrid inverter charger. They not only invert DC power to AC power from your solar panels, but they can also convert DC power to AC power to charge your batteries.

Hybrid inverters, like the Victron Multiplus series, also can mix power from a shore or generator supply and your batteries. This can allow you to operate on a smaller generator or shore power supply without overloading the generator or breaker.

Can More Than One Inverter be Used at the Same Time?

Yes! While systems can get complicated, inverters like the Victron multiplus can parallel together to increase capacity. Some inverters can even parallel together to offer higher voltage outputs like 240V.

Sometimes RV’s will install multiple inverters to power dedicated items. For example, if an RV has a residential fridge, running one large inverter would not be as efficient as running a smaller one just for the fridge. In this case, the larger primary inverter could be shut off to save power while the smaller unit stays on to run the fridge.

Do You Need an Inverter for Your RV?

This entirely depends on your style of RVing. Do you plan to park at a campground or RV park with full hookups 99% of your time on the road? If so, you probably won’t need an inverter. This is because your RV will always be connected to shore power (i.e., AC power).

Do you plan on spending time off-grid? Do you want to boondock in amazing, secluded places? If your answer is yes, you’ll definitely need an inverter. Even if you don’t have solar, you’ll still need an inverter to turn your DC power from your batteries into usable AC power. 

Depending on the devices you need to charge, you may only need a small 1,100-watt inverter. However, we recommend having a way to invert DC power to AC power so you can at least charge your phone, laptop, and whatever else you’ll be using on the road. 

⚡️ Check out our selection of Inverters in our shop to see which ones meet your power needs. You can also always call our support team at (855) 292-2831 to help figure out the requirements of your system.

Be Prepared to Be Off-Grid

If you plan to spend some time off-grid, you’ll need an inverter to turn solar and battery power into usable AC power. This is because most appliances can only run on AC power. But that leaves the question: What size inverter do I need for my RV?

The answer to this question is determined by multiple factors, including the number of watts your devices require, your battery bank size, and your travel style. The truth is, every RVer’s electricity system will be a little bit different. It’s really all about finding the perfect setup that enhances your sense of freedom on the road!

Do you have any more questions about RV inverters? Leave them in the comments below!

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Want To Learn More About Electrical Systems and Lithium Batteries?

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