What Size Generator For RV AC? (13,500 & 15,000 BTU)

If you’re a new RV owner, you may be wondering what the best size generator is for an RV air conditioning unit. Unfortunately, that question has some weight to it as it depends on the size of the AC and the level of cooling output an individual requires.

However, from personal experience, I have found the best generator size for RV AC is 2,000 – 4,000 watts.

What Size Generator For RV AC? (Explained For Different RV AC Sizes)

Having an AC unit for your RV makes sleeping far more comfortable, especially in the heat of summer after a full day in the sun. Thankfully, with the right-sized generator, you can power most RV AC units without turning off your other appliances.

RV AC Generator Size

11,000 BTU RV AC

An 11,000 BTU air conditioner needs a generator that has at least 1600 starting watts and 1,010 running watts. Since it’s a smaller AC unit, you may need a second air conditioner to keep your RV cool enough. That means you need to double your wattage needs. Plus, you need to factor in any other appliances you want to run and their respective wattage needs.

13,500 BTU RV AC

Bumping up to a 13,500 BTU air conditioner requires a starting wattage of 2800 and 1800 running watts. It would be best if you had at least a 4,000-watt generator, but it is unlikely to accommodate additional AC units or other appliances. If you want to use more appliances or add on a second AC unit, you will require an additional generator.

15,000 BTU RV AC

A 15,000 BTU air conditioner requires a whopping 3300 starting watts and 2000 running watts. Even with a 4,000 or 5,000-watt generator, you won’t be able to run anything else, but you probably won’t need a second AC unit to keep cool.

Quick Comparison Of Generator Sizes For RV Air Conditioners

The size of the generator in your RV will help determine what size of generator is necessary to run the appliance efficiently. But what size generator is required for an RV with two AC units? Take a look at the table below to compare generator sizes for RV air conditioners.

RV AC Size BTURV AC Size Per WattageGenerator Size (Watts)
11,000 BTU1,100 watts2,000 watts
13,500 BTU1,350 watts3,000 watts
15,000 BTU1,500 watts4,000 watts

How To Calculate The Size Of Generator For My RV AC?

The best way to calculate the size of the generator necessary for an RV AC is to first determine the wattage size of the unit. After converting BTUs to watts, you will better understand how big a generator you need to run the AC unit.

For instance, a 13,500 BTU AC unit converts to 1,350 watts, meaning that you need at least a 3,000-watt generator to run the AC unit. You may be wondering if a 2,000-watt generator will run a 13,500 BTU RV air conditioner because 2,000 is more than 1,350.

While it is possible, you risk pulling too much power from the generator when starting the air conditioner. The starting wattage for the AC unit is typically much higher than the running wattage. Therefore, it is necessary to have more power from the generator than the size of the AC unit.

Here is a breakdown of the starting vs. running wattage necessary for various AC unit sizes:

RV AC Size BTUStarting WattageRunning Wattage
11,000 BTU1,600 watts1,010 watts
13,500 BTU2,800 watts1,800 watts
15,000 BTU3,300 watts2,000 watts

Costs Associated With Using a Generator For Cooling Your RV

The cost of using a generator for cooling your RV depends on several factors, including fuel type and costs. Generators typically run on diesel, gas, or propane, but there are also green-power options, like solar-powered generators.

Initial Investment

Start with the initial investment when you purchase a generator. Portable generators cost at least a few hundred dollars on the cheap end but won’t likely have the wattage you need. To get a 4,000 or 5,000-watt generator, expect to pay more than $500.

Solar-powered generators cost substantially more upfront, to the tune of $1,000 or more. However, you don’t have related fuel costs, and they can last up to 20 hours after a day of sunshine.

Fuel Costs

The fuel costs are where generators can drain you. If you want to run the AC all night, that increases the generator run time and fuel usage.

Using gasoline or diesel gets expensive when oil prices skyrocket. The average 4000-watt gasoline-powered generator has a three or four-gallon tank and can run for up to 12 hours, depending on the load size. If gas is $3 per gallon, you can plan on $9 to $12 per day.

Running a generator on propane is more challenging to figure out. While propane burns cleaner, it’s less efficient. A generator can last five hours with 20 pounds of propane, meaning you won’t make it through an entire night.

Generator vs. RV Battery

AC units require a lot of electricity to operate. To use the RV battery for air conditioning, you need to shore it up with support, like solar panels and additional batteries. Consequently, it is more cost-effective to run the AC with a generator than to use the RV battery.

Generator Vs RV Battery

People Also Ask (FAQ)

How long can you run RV ac with a generator?

You can run your RV AC with a generator 24-hours a day, depending on how many gallons of gas the generator holds. For example, 2-gallons of gas will keep the AC running for approximately 8-hours. Therefore, a 6-gallon tank will keep the AC running all day and night.

How long do generators last?

Generators typically last approximately 3,000 hours. Therefore, if you run your generator for 1000 hours out of the year (or 2-3 hours per day), it will last about 3 years. Ensure to conduct research on a generator and look up reviews to determine how long it generally lasts.

Related Article RV Air Conditioning Problems

What fuel does an RV generator use?

Generators use various types of fuel. Built-in RV generators typically use either diesel, gas, or propane. If using an external generator, you have the option to use a solar-powered generator.


Choosing a generator size to run a 13,500 or 15,000 BTU AC unit is a daunting task. Luckily, you can determine what size generator is necessary to efficiently run the air conditioning unit by converting BTUs to watts and understanding starting and running wattage.

The most common RV generators range from 2,000 to 4,000 watts to meet all energy needs.

Josh Mitchell

Josh Mitchell

My name is Josh and I am obsessed with DIY and improving my family home. HVAC topics can be tricky for homeowners so I decided to share my knowledge on the subject. When I am not working on DIY projects, you can find me at the beach or my local coffee shop.