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

Choosing the right size generator to run an RV AC is essential for ensuring both efficient and safe operation. RV generators vary significantly in size, ranging from 2,500 watts to 12,500 watts. The ideal size depends on several factors, particularly the number of appliances you intend to operate simultaneously and the specific requirements of your RV air conditioner.

Typically, air conditioners need about 1,500 to 1,800 watts for continuous operation, but the initial startup surge can reach between 2,800 and 3,500 watts. This surge is a vital consideration when choosing a generator, as failing to account for it may lead to generator overload or tripped breakers.

Recommended RV Generator Sizes to Run AC

So, what size generator is needed to run AC in an RV? To ensure that your RV generator can accommodate continuous power needs and the initial surge of your air conditioner, consider the following general recommendations based on common air conditioner sizes:

13,500 BTU AC Unit:

• Running Wattage: Approximately 1,500 watts

• Starting (Surge) Wattage: Up to 2,800 watts

• Recommended Generator Size: At least 3,000 watts

15,000 BTU AC Unit:

• Running Wattage: Approximately 1,800 watts

• Starting (Surge) Wattage: Up to 3,500 watts

• Recommended Generator Size: At least 4,000 watts

These suggested sizes ensure that your generator can meet the operational demands of both running and starting your RV’s air conditioner. However, other considerations may also affect your final choice of generator.

Helpful tip from our team: As generators are constantly evolving, their motor size also changes, impacting their capabilities. To ensure a successful start-up, carefully consider the "CC" (cubic centimeters) size of the motor. This step is crucial to avoid any potential failures during start-up.

When reviewing generator specifications, you’ll want to pay attention to the CC size since generator engine displacement often correlates with power output and fuel capacity. Remember, a higher number typically means better performance.

 Portable generators with an output of 2000 to 2200 watts can range from 79cc to 120cc.

Factors Influencing RV Generator Size Selection

When selecting what size generator for RV AC, it is important to consider more than just the wattage of the air conditioner. Additional factors that may influence the required generator size include:

• Additional Appliances: If you plan to operate additional devices, such as a microwave, refrigerator, or electric coffee maker, you must factor in their total wattage. Ensure that the generator can support the combined load of multiple appliances running at the same time.
  

• RV Electrical System: Ensure that the generator's output aligns with your RV's electrical system, whether it is 30-amp or 50-amp, to guarantee compatibility. Using a generator with insufficient power can lead to complications within the RV's internal systems.
  

• Altitude and Temperature: The performance of your generator may diminish at higher elevations or in extreme weather conditions. If you are traveling through mountainous regions or very hot environments, you might require a more powerful generator to sustain optimal functionality.

How a Soft Starter Affects Generator Size Selection

An RV air conditioner soft starter, such as Micro-Air’s EasyStart Breeze™, can significantly influence what size generator your RV air conditioner will need. This device minimizes the initial power surge your air conditioner requires during startup. Typically, an RV air conditioner demands a substantial surge of electricity to power up, which can surpass the capacity of smaller generators or cause circuit breakers to trip. However, a soft starter can reduce the start up power surge of an RV air conditioner by as much as 70%.

For instance, after installing a soft starter, you could operate a 13,500 BTU air conditioning unit with a 2,000-watt generator, enhancing energy efficiency, decreasing weight, and conserving fuel. As we mentioned above, generator engine displacement typically correlates with power output and fuel capacity. Therefore, using a soft starter allows you to choose a generator with a smaller CC engine without sacrificing performance. Additionally, improving generator compatibility and lowering the startup power demand can prolong the lifespan of your air conditioning unit and other connected appliances.

How to Calculate Generator Size for RV AC with a Soft Starter

While a soft starter enables the use of a smaller generator for your RV air conditioning unit, it is crucial to accurately calculate the appropriate generator size for your requirements. Here is a straightforward formula to calculate generator size for RV AC:

Watts = Amps × Voltage

Step 1: Find the Total Amps

To establish the total current consumption of your air conditioning unit, sum the Compressor RLA (Run Load Amps) and the Fan RLA(s) indicated on the nameplate of your AC unit. This calculation will yield the total amperage required for the unit's operation.

Step 2: Compute the Wattage Requirement

Multiply the total amperage by the voltage, which is generally 120 volts for most RV air conditioning systems.

• For a 13.5K BTU AC Unit: Watts = 15 Amps × 120 Volts = 1,800 watts

• For a 15K BTU AC Unit: Watts = 16.2 Amps × 120 Volts = 1,944 watts

Step 3: Add a Safety Margin

To accommodate power variations and the potential load from other devices, add 20-30% to the calculated wattage.

• For a 13.5K BTU unit with Safety Margin: 1,800 watts × 1.3 = 2,340 watts

• For a 15K BTU unit with Safety Margin: 1,944 watts × 1.3 = 2,527 watts

Step 4: Choose an Appropriate Generator

Select a generator that meets or surpasses the wattage requirement (continuous power rating) including the safety margin. For example, a 3,000-watt generator would be adequate for a 13,500 BTU AC unit, while a 4,000-watt generator would be suitable for a 15,000 BTU AC unit.

Consider the impact of a soft starter on these calculations. With a Micro-Air EasyStart installed, the initial surge in power is significantly reduced, enabling the use of a smaller generator. For instance, a 2,000-watt generator may be sufficient for a 13,500 BTU AC unit equipped with a soft starter. 

Here’s an EasyStart Breeze soft starter generator size chart from Micro-Air for reference:

* Amps will vary by manufacturer and model family. These are only average estimates.

** Generator size is rated running watts, assuming starting watts are about 1.4 times more. The minimum generator size also assumes there are no other significant household loads running when the compressor tries to start.

Make the Most of Your RV AC with the Right Generator and Soft Starter

Selecting the appropriate generator size for your RV air conditioner is essential for ensuring comfort and energy efficiency. By taking into account both the running and starting wattage of your AC unit as well as any additional appliances, you can choose a generator that fulfills your requirements.

A soft starter will help you effectively mitigate startup power surges, allowing for the use of a smaller generator and improving overall energy efficiency. By reducing the startup strain on your RV's air conditioning unit, you also prolong the lifespan of both your air conditioning system and other connected devices, making this a wise investment for any RV owner.

Since 1983, Micro-Air has led the way in innovative power management solutions tailored for RV owners. Their EasyStart Breeze™ soft starter significantly decreases startup power demand by up to 70%, enabling you to operate air conditioners and multiple appliances on smaller, more fuel-efficient generators. All Micro-Air products are proudly designed, tested, and supported in the USA. 

You may also be interested in:

• Can You Run an AC with Solar Power in an RV?

• How Many Amps Does an RV AC Draw?

RV Generator Sizing Questions

Have more questions about an RV generator’s sizing? Here are some common questions and answers to consider.

What size generator should I run a 15,000 BTU air conditioner?

For a 15,000 BTU AC unit, you will need a generator that delivers at least 4,000 watts to meet both the running and startup power demands.

What size generator should I run a 13,500 BTU air conditioner?

For a 13,500 BTU AC unit, a generator with a minimum output of 3,000 watts should be adequate, provided the air conditioner is the main appliance in use. If you plan to operate additional devices simultaneously, a larger generator may be necessary.

What size generator do I need for an RV with 2 AC Units?

If your RV features two air conditioners, you will require a generator capable of supporting their combined wattage. For instance, with two 13,500 BTU units, a generator rated at least 6,000 watts would be a suitable starting point.

Note: This article is for informational purposes only; Micro-Air does not make recommendations or provide support outside of Micro-Air products.