What Size Generator Do You Need to Run an RV Air Conditioner?

Let's face it: even the most outdoorsy adventurers among us don't love the idea of sweating in a cramped tent in sweltering summer temperatures. One of the biggest perks of RV camping is the fresh, cool air provided by your air conditioner. With your motorhome's AC unit, you can enjoy a relaxing day (or night) in your camper, sipping an ice-cold drink and congratulating yourself on your decision to buy an RV.

However, if you plan on boondocking and enjoying your RV off the beaten path (and away from shore power), you probably want to run your AC to keep things cool. For this, you'll need a generator.

So what size generator do you need? One that's big enough to run your AC as well as everything else you plan to run. You don't want to enjoy your AC but lack the ability to use your lights, charge your phone, or power your fridge!

We'll help you get started figuring out your AC power demands below.

How Many Watts Does an RV AC Use?

To choose the right size generator, you need to know the starting (surge) watts and running (rated) watts required by your RV's air conditioning unit.

Every air conditioner is different, but they all require a specific number of "start up watts"—the initial burst when the unit is turned on. Each unit will also require a certain number of "running watts," which will be lower (sometimes significantly) than the start-up watts needed.

RV air conditioners are typically either 15,000 Btu (British thermal units) or 13,500 Btu, although other sizes exist as well. This is basically the cooling capacity of your AC. A 15,000 Btu unit has a greater cooling capacity but will require more power—about 5,100 starting watts and about 1,600 running watts, on average. A 13,500 Btu unit draws less power—about 3,800 starting watts and about 1,300 running watts.

You'll need to make sure your generator can handle both the starting and running requirements of your unit, as well as the starting/running watts of all your other appliances you plan to run. Check the manufacturer's label or manual provided for your appliances to verify how much power they draw.

In general, it's better to have more power than not enough. If you're wavering between two generator sizes and think you can get by with the smaller size, strongly consider going one size up. The extra power will allow you some breathing room if you end up using more power than you initially plan. (Or if you forget to let the washing machine finish before turning on the microwave.)

Note: These numbers are averages based on information obtained from RV AC manufacturers as well as our own testing. Starting wattage on air conditioners can vary greatly depending on several factors, including the assistance of built-in capacitors and cold starts.

Calculating Generator Requirements to Run Your AC

If you plan on running your AC and other appliances with a generator, your generator must meet or exceed the demands of the devices it will power. That means that you need to calculate the average power demand (watts) of all the appliances you plan to run, not just your AC.

It's always best to start your generator without a load connected, then add your devices one at a time. It's also a good idea to connect your devices in order from highest starting watts to lowest starting watts. Most likely, your AC will require more starting watts than anything else, so typically you'd want to start up your AC first.

As an example, let's say we plan on running the following appliances with the following power requirements with our generator:

Appliance

Running Watts

Starting Watts

13.5k BTU AC

1,300W

3,800W

Refrigerator

800W

1,600W

32" LCD TV

150W

Floor Fan

100W

To find the total starting watts required, add the starting watts for the device with the highest value (in this case, our AC unit) to the running watts of the other devices.

EX: 3,800 + 800 + 150 + 100 = 4,850 starting watts

To find the total running watts required, add together the running watts for all appliances.

Ex: 1,300 + 800 + 150 + 100 = 2,350 running watts

In this example, we'll need a generator with at least 4,850 starting watts and 2,350 running watts. For help with more precise calculations, typical power demands of RV appliances, and additional need-to-know information on generators, check out our generator overview.

Which Generator Will Run My RV Air Conditioner?

At etrailer, we perform numerous tests on generators to put them through real-world experience. An extensive part of this testing includes starting and running RV air conditioners.

The following table will help you decide which generator has enough power to handle this critical function in your RV. Select the generator type you need from the chart below, then scroll down to find the available generators that can handle your load.

NOTE: Decibel (dB) levels are measured at 25 ft away in standard mode at 1/4 load, unless otherwise indicated. Normal conversation is 60 dB.

GROUP A

# 333-0002

Brand: etrailer

Start Type: Manual

Starting Watts: 3,200

Running Watts: 2,900

Noise Level: 58 dB

# 333-0003

Brand: etrailer

Start Type: Remote

Starting Watts: 3,200

Running Watts: 2,900

Noise Level: 58 dB

GROUP B

# 333-0001-2

Brand: etrailer

Start Type: Manual

Starting Watts: 3,800

Running Watts: 3,000

Noise Level: 58 dB

# 333-0001-0002

Brand: etrailer

Start Type: Manual

Starting Watts: 4,900

Running Watts: 4,275

Noise Level: 58 dB

# 333-0002-2-0007

Brand: etrailer

Start Type: Manual

Starting Watts: 6,000

Running Watts: 5,500

Noise Level: 58 dB

# 333-0003-2-0007

Brand: etrailer

Start Type: Remote

Starting Watts: 6,000

Running Watts: 5,500

Noise Level: 58 dB

GROUP C

# 333-0004

Brand: etrailer

Start Type: Remote

Starting Watts: 4,500

Running Watts: 3,600

Noise Level: 67 dB

# 289-SUA4500

Brand: A-iPower

Start Type: Manual

Starting Watts: 4,500

Running Watts: 3,500

Noise Level: 68 dB*

# 289-AP5000

Brand: A-iPower

Start Type: Manual

Starting Watts: 5,000

Running Watts: 4,000

Noise Level: 68 dB at 1/2 load*

# 333-P05703

Brand: Firman

Start Type: Remote

Starting Watts: 7,125

Running Watts: 5,700

Noise Level: 72 dB

# 289-SUA9000E

Brand: A-iPower

Start Type: Electric

Starting Watts: 9,000

Running Watts: 7,000

Noise Level: 76 dB*

# 333-P08003

Brand: Firman

Start Type: Electric

Starting Watts: 10,000

Running Watts: 8,000

Noise Level: 74 dB

*Measured at 23' away

GROUP D

# 333-0005

Brand: etrailer

Start Type: Electric

Starting Watts: 4,500

Running Watts: 3,600

Noise Level: 67 dB

# 333-H05751

Brand: Firman

Start Type: Electric

Starting Watts: 7,125

Running Watts: 5,700

Noise Level: 74 dB

# 333-H08051

Brand: Firman

Start Type: Electric

Starting Watts: 10,000

Running Watts: 8,000

Noise Level: 74 dB

About the Author

As a content writer for etrailer, I might spend my morning loading and unloading a bike on five different bike racks to figure out which is easiest to use. I might be in the parking lot, taking pictures of an impressive RV battery setup our techs came across in the shop and discussing the benefits of the setup with the owner. I might spend an afternoon in a manufacturer training classes for some hands-on experience with new products, and then sit down to assemble all this information into a coherent article.

At etrailer, one of our core values is that we are always learning, and I learn something new every day. I start each morning with the goal in mind of taking all of this information and figuring out the best way to answer the questions people ask us (and the ones they don’t know to ask yet), and helping people get the solutions they need to make their lives easier, safer, and more fun. I’m a DIYer at heart, so it brings me great joy to help a fellow DIYer find what they’re looking for, whether that’s a product, an answer, or a community.

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Written by: Amber S.

Updated On: 11/22/19

Will

10/4/2020

Is there any way to run a parallel system using solar for 50 amp, around 6k watts total? I'm looking for a portable solar inverter generator(s) plus panels that I can parallel a 50 amp connection for our RV... The RV has two A/C units (a 15k BTU, and a 13.5k BTU). Thanks!

Jon G.

10/5/2020

I'm not aware of any generators that you can connect solar panels directly to so the only way I really know how you'll be able to do this is by using a whole setup with an AC/DC converter panel so that you can have both AC and DC connections for your trailer power.

Will

10/5/2020

@JonG thanks for your response. I've found several but not the right wattage. Jackery Portable Power Station Explorer 1000, and I believe generac carries them as well..

Jon G.

10/5/2020

@Will We actually do have some portable power stations like the Jackery that you mentioned - I thought you were referring to a standard-type generator. These are designed more for smaller applications or emergency power in the event of a power failure and aren't really meant to power a whole camper. They are essentially big batteries with a smart charger built in and multiple ways for you to draw power from it. For your application it sounds like you'd want to go with a big battery banks and then add solar to that as well.

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