The inverter – simplified! What you need to know

The inverter is a bit of RV technology that sometimes baffles people. Some folks don’t know if they have one, or where it’s located. Others aren’t clear about what they can use the inverter to power, and what they can’t. 

Similar to topics like RV solar power and tire pressure monitoring, understanding the inverter is easier than you may think.

Here’s a simple overview of what the average RVer needs to know, without diving into technical jargon or edge cases.

What is the inverter and what does it do?

An inverter is a device that allows you to plug things into electrical outlets even when the trailer itself isn't hooked up to campground power. Without an inverter, the electrical outlets in your Airstream will not work if you’re not plugged into campground power.

This means that if you are camping without hookups (boondocking), you won’t be able to charge or use things that require an outlet – like charging your laptop when you're enjoying a quiet boondocking spot – unless you are using an inverter.

The inverter makes this possible through a little electrical trick: it turns the power from the batteries, which is 12 volt Direct Current (DC), into 120-volt Alternating Current (AC),* which is the same power you use in your house. So with the inverter switched on, you can watch TV, play DVDs, plug in your laptop, and charge your devices at any time.

Where is the inverter in my Airstream?

Most Airstreams made in the last decade (except Basecamp and Bambi) have a factory-installed inverter. Look for a little control panel that has a push-button to turn it on and off. Although the control panel may look different depending on your model, in most trailers it looks similar to this: 

Older Airstreams might have an inverter too, but those are usually owner-installed, and their controls will look different.

How to use the inverter wisely

The fact that at the push of a button you can watch TV and plug in laptops and other devices while you’re boondocking probably sounds pretty good to you. And it is. But keep in mind the inverter does have a few limitations. 

The most important one is: the inverter isn't particularly efficient. 

When it’s turned on and you’ve got something plugged into it, the inverter itself consumes (wastes) 10-20% of the power coming from the batteries. That means there's a larger hit to the batteries than you might think, whenever you use it to charge a device or watch a DVD. 

Put another way, you’re always using 10-20% more battery power than you think to run things off the inverter.

So let’s cover a few essentials for using the inverter wisely. 

1. Use inverter power sparingly

You can (and will!) run out of power if you're not thoughtful about how long you keep the inverter turned on.

The inverter runs off the batteries in your Airstream. And the factory-installed batteries are designed to support the Airstream for a day or two of "typical" needs.

So realistically, if you’ve got factory-installed (non-lithium) batteries, and you turn on the inverter and use your laptop computer all day, there won't be much power left for the next day—unless you also have solar panels or a generator.

My advice: If you're a frequent off-grid camper and heavy user of the inverter, talk to a good service center about adding more battery capacity or switching to lithium batteries.

2. Use only low-power appliances

The standard inverter installed on most Airstream trailers up to model year 2023 has a rated capacity of 1,000 watts. That's plenty for low-power devices like the TV, DVD player, toothbrush charger, or a laptop, but not nearly enough for some other appliances – for example, a toaster. 

Starting with the 2024 model year, Airstream upgraded the inverter to 2,000 watt capacity in most trailers, and a whopping 3,000 watts in the Trade Wind model. These higher capacity inverters allow you to plug in more power-hungry devices, but you still need to be mindful of what you plug in because they’ll chew up your batteries like a hungry bear.

Rule of thumb #1: If it has a heating element, you probably shouldn’t try to run it from the inverter. 

This includes a hair dryer, toaster, coffee pot, space heater, waffle iron, electric skillet, etc. These things often use up to 1,500 watts, which will overload the smaller inverters and stress the bigger ones. If you overload the inverter it will probably shut itself off—and it may burn out permanently.

Rule of thumb #2: If it has a motor, think twice before using it. 

Most things with electrical motors need too much power. You probably already know that the air conditioner and microwave will never work if you’re not plugged into shore power. They aren’t connected to the inverter at all, so they simply won't go on. 

But you should think twice about running a vacuum cleaner or another appliance with a motor. At the very least devices like these will drain the batteries quickly – and worst case, they might overload the inverter.

3. Check the label before you try to plug it in

Not sure if the device you want to plug in is safe for the inverter? Every electrical device has some sort of labeling to tell you how much power it needs. For example, this is the label printed on my laptop charger: 

I apologize because this involves a tiny bit of math, but all you need to know in order to read a device’s label is that amps x volts = watts. 

(I promise that’s the most complicated math we’ll cover here.)

So, looking at this label, we see "Input: 100-240V." That means this charger will operate on any voltage from 100 to 240. (Which means you can use it in Europe!) In North America, it will run quite happily on 120 volts.

Now let’s take that number and multiply it by the next number. If you squint you'll see that it says "~0.75A" which means it draws a maximum of about 0.75 amps. 

Remember the equation from above: amps x volts = watts. So by multiplying 120 x 0.75, we come up with 90 watts. And that’s good news because 90 watts is far below the 1,000 watt rating of my inverter. So I know it will be no problem to use this charger.

(If you’re wondering why it’s labeled as a “30W USB Power Adapter” when the fine print says it needs 90 watts, it’s because there’s some power lost along the way. The adapter outputs 30 watts, but it can consume quite a bit more power than that.)

My advice: Do this bit of math on any device you want to plug into the inverter.

And just for geeky fun, take a look at some of the things you might plug in. You might be surprised (dare I say "shocked"?) by the range of power requirements that a coffee maker or iPhone charger requires.

4. Turn the inverter OFF when you're not using it

Even in "standby" mode with nothing plugged in, the inverter uses power. It's not much at any given moment, but just like a dripping faucet can eventually fill a sink, that power drip adds up to quite a lot over the course of a couple of days. 

My advice: Only turn on the inverter when you really need it, and turn it off when you don’t. Like after you finish watching a movie.

5. Be mindful of the heat

Remember that 10-20% power waste we mentioned earlier? It’s released into the air as heat. Although the inverter has a pair of fans to keep it cool, on a really hot day, the inverter can get too hot—and that's bad for the longevity of the inverter.

Most of the time this won't be a problem because frankly, only the hard core among us are willing to boondock in high temperatures. But if you pull into a boondocking spot after a sunny day of towing and the interior of the Airstream is over 104 degrees F (which can happen easily in the summer), the inverter will be over its safe maximum temperature. 

My advice: If the Airstream interior is hot, wait for the internal temperature to drop below 104 degrees F before switching on the inverter. Monitor this on your wall-mounted thermostat.

6. Use the inverter for more than device charging and DVDs

Although most people go for these two common uses, the inverter is handy for other jobs too. Here's one of my favorite hacks: Plugging in a portable air compressor to top up the trailer tires during a trip. 

I did the math described in tip #3 to calculate that my inexpensive portable compressor draws just 130 watts of power. So even though it has a motor, it's well within the capacity of my 1,000 watt inverter. Anytime I need to top up the tires, I just flip on the inverter and plug in my compressor. Beats the heck out of trying to find a power outlet or a gas station air compressor.

An important note: The exterior outlet on your Airstream may not be connected to the inverter. So for a hack like this one you may need to run a good heavy-duty extension cord from one of the interior outlets. You should carry one in your rig.

That's probably all most people need to understand about inverters. I hope this simple overview helps you understand that it’s a really handy device – as long as you understand its limitations and use it in moderation.

 * The voltages mentioned are not exact. Household current, for example, can run from 108 volts to 132 volts and still be considered normal. The WFCO brand inverter in a late model Airstream is actually designed to output 115 volts. Likewise, a "12-volt" battery is really going to put out about 12.6-13.0 volts when fully charged. This voltage drops as the battery is depleted. You didn't need to know this and it really won't change anything written here, but I mention it because otherwise, somebody will feel the need to "correct" me.