An RV air conditioner uses power measured in watts. How many watts does an RV air conditioner use? It is not one fixed number. The amount of power needed changes based on the air conditioner’s size and whether it is just starting up or running steadily. A typical RV air conditioner can use anywhere from about 600 watts to over 2000 watts when running. But when it first turns on, it needs a big burst of power, often called starting watts, which can be 2 to 3 times higher than the power it uses when just running. This means an RV AC might need 1500 to 3500 watts or more just to start its cooling motor.
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Grasping RV Air Conditioner Power Use
Thinking about RV air conditioner power consumption means looking at how much energy your AC unit takes to work. Power is often talked about in watts. Watts tell you how much work is being done by the electricity at any given time. The higher the watts, the more power the AC is using.
Why is knowing the power use important? Because you need to make sure your power source, like your generator, batteries, or the power plug at the campground (shore power), can give the AC enough energy. If it can’t, the AC won’t turn on, or worse, it could damage your power system or the AC unit itself.
Power use is not always the same. It changes depending on what the AC is doing.
* When it starts, it pulls a lot of power for a very short time.
* Once it is running smoothly, it pulls less power, but it uses that power continuously.
Knowing these two types of power needs – starting and running – is key to figuring out what kind of power setup you need for your RV.
Starting Watts RV AC vs. Running Watts RV AC
This is a very important idea when it comes to RV air conditioners. An AC unit has a motor called a compressor. This compressor is what makes the magic happen – it moves the stuff (refrigerant) that cools the air.
When the compressor first starts, it needs a big push of power to get going. Think of pushing a heavy box. It takes a lot of effort to get it moving (starting watts). Once it is sliding, it takes less effort to keep it moving (running watts).
- Starting Watts RV AC: This is the high amount of power the AC pulls for a quick moment, usually just a second or two, when the compressor kicks on. This is the peak power need.
- Running Watts RV AC: This is the lower, steady amount of power the AC uses continuously after the compressor is running and cooling the air. This is the average power need while the unit is working.
For example, an RV AC might need 3000 watts to start but only 1500 watts to run. That big difference is why many RVers need to think carefully about their power sources, especially generators. A generator or inverter might handle the running watts fine but trip or fail when hit with the high starting watts.
Deciphering RV AC Amperage
Watts and amps are related. RV AC amperage tells you the flow of electric current. Watts tell you the total power. The simple rule is:
Watts = Volts x Amps
In most RVs in North America, the main power is 120 volts (V). So, if an AC uses 10 amps at 120 volts, it uses 10 * 120 = 1200 watts.
Knowing the amperage is useful because power sources like shore power outlets and circuit breakers are often rated in amps (e.g., 30 amp service, 50 amp service). You need to make sure the AC’s amperage draw does not go over the limit of the circuit it is plugged into.
Just like watts, there’s a starting amperage (sometimes called Locked Rotor Amps or LRA) which is much higher than the running amperage. This relates directly to the starting watts.
- Running Amperage: The steady current flow while the AC is cooling. Typically 8-15 amps for one unit at 120V.
- Starting Amperage: The high current flow needed to start the compressor. Can be 30-60 amps or even more for a brief moment.
Checking the tag on your RV AC unit is the best way to find its specific running amperage and sometimes the LRA (starting amperage).
How BTU Rating Affects RV AC Power Usage
Air conditioners are rated by how much heat they can remove. This is measured in BTUs (British Thermal Units). A higher BTU number means a more powerful AC unit that can cool a bigger space or cool faster.
The BTU rating RV AC power usage is a direct link. Generally, an RV AC with a higher BTU rating will use more watts (both starting and running) than an AC with a lower BTU rating.
Common RV AC sizes:
* 13,500 BTU: This is a very common size for many RVs.
* 15,000 BTU: A larger size, often used in bigger RVs or for better cooling in hot weather.
A 15,000 BTU unit will typically use more power than a 13,500 BTU unit.
Here is a general idea of power use based on BTU size (these are estimates and can vary by model):
| BTU Rating | Running Watts (Approx) | Starting Watts (Approx) | Running Amps (Approx @ 120V) |
|---|---|---|---|
| 13,500 | 1200 – 1500 | 2500 – 3000+ | 10 – 12.5 |
| 15,000 | 1500 – 1800 | 2800 – 3500+ | 12.5 – 15 |
Keep in mind, these are just averages. The actual power use of your specific unit can be found in its manual or on a sticker on the unit itself.
Powering Your RV AC: Shore Power, Generators, Batteries, and Inverters
There are a few main ways to get power to your RV air conditioner.
Shore Power for RV AC
This is the easiest way to power your AC. Shore power for RV AC means plugging your RV into an electrical outlet, usually at a campground or your home. Campground power posts provide 120V AC power.
The amount of power available from shore power depends on the outlet’s rating:
* 30 Amp Service: This is common for many smaller to medium-sized RVs. At 120V, a 30 amp hookup gives you a total of 30 amps * 120 volts = 3600 watts of power.
* 50 Amp Service: This is common for larger RVs, especially those with two air conditioners. A 50 amp hookup is actually two separate 120V, 50 amp lines. This gives you a total of 50 amps * 120 volts on one line + 50 amps * 120 volts on the second line = 12,000 watts total power. However, the RV splits loads between these two lines. You can usually run both ACs and other appliances on 50 amp service.
If you have 30 amp service, running a single 13,500 or 15,000 BTU AC unit is usually fine. It will use most of your available power, so you might need to turn off other high-power items like a microwave or hair dryer while the AC is running. With 50 amp service, you have plenty of power for one or even two ACs plus other things.
RV Generator Size for AC
When you are not plugged into shore power, you can use an RV generator. A generator makes its own electricity. To run your AC, you need to make sure your generator is big enough to handle the AC’s power needs, especially the high starting watts.
RV generator size for AC is measured in watts or kilowatts (kW). 1 kW = 1000 watts.
You need a generator that can supply at least the running watts of your AC, plus extra to handle the starting watts of the AC and any other appliances you want to run at the same time.
- For a single 13,500 BTU AC, you will likely need a generator that can provide at least 2800 to 3500 starting watts (surge) and 1500-2000 running watts. A 3000-watt or 3500-watt generator is often recommended.
- For a single 15,000 BTU AC, you might need a generator with 3000 to 4000+ starting watts and 1800-2200 running watts. A 3500-watt or 4000-watt generator is better.
- If you have two AC units (common on 50 amp RVs), you need a much larger generator, possibly 5000 watts or more, or two smaller generators working together (paralleled).
Always check the generator’s peak (surge) wattage and continuous (running) wattage. The surge wattage must be higher than your AC’s starting wattage.
Battery Bank for RV AC
Can you run an RV air conditioner on batteries? This is tricky for standard rooftop ACs. Standard RV ACs run on 120V AC power, just like home appliances. RV batteries store 12V DC power.
To use battery power for a standard AC, you need two things:
1. A large battery bank for RV AC. Batteries store energy. Running a standard AC uses a lot of energy, very quickly. You would need a huge battery bank (many batteries) to run a standard AC for more than a short time (maybe 1-3 hours depending on size and conditions).
2. An inverter capacity for RV AC. An inverter changes the 12V DC power from your batteries into 120V AC power that the AC can use. The inverter must be powerful enough to handle both the running watts and the starting watts of the AC.
Running a standard AC on batteries alone is usually not practical for most RVers. It needs a massive battery bank and a large, expensive inverter. This is why most RVers use shore power or a generator for AC.
However, there are some newer 12V RV air conditioner power draw options appearing on the market. These are designed to run directly off your RV’s 12V battery system. They avoid the need for a large inverter and are more efficient with DC power. Their power draw is much lower, often in the 50-150 amp range at 12V (which is 600-1800 watts). These units are usually smaller and have lower BTU ratings (often around 7,000-9,000 BTU), meaning they cool less space than typical rooftop units. They are great for small vans, cooling a bedroom overnight, or reducing generator run time, but may not cool a large RV effectively in hot weather. Running even a 12V unit for a long time will still drain batteries quickly, so you need good battery capacity and a way to recharge (solar panels are key here).
Putting It Together: Matching AC Needs to Power Supply
Let’s look at how the AC’s power needs match up with different power sources.
Imagine you have one 13,500 BTU RV AC unit.
-
Shore Power (30 Amp): You have 3600 watts total available. Your AC might need 1400 running watts and 2800 starting watts.
- Can it start? Yes, 2800 starting watts is less than 3600 watts available for a brief moment.
- Can it run? Yes, 1400 running watts is well within the 3600 watts available, leaving power for other things (though you need to watch your total draw).
-
Shore Power (50 Amp): You have 12000 watts total available.
- Can it start and run? Easily. Plenty of power for this AC and much more.
-
3000 Watt Generator: This generator might have a running rating of 2800 watts and a surge rating of 3300 watts.
- Can it start the AC (2800 starting watts)? Maybe. The 3300-watt surge is just enough or might be too low depending on the specific AC unit’s exact starting draw and the generator’s true capacity. It’s tight.
- Can it run the AC (1400 running watts)? Yes, the 2800 running watts rating is enough.
- Note: This example shows why a 3500-watt or 4000-watt generator is often safer for a 13,500 BTU AC – it provides more cushion for the surge.
-
Battery Bank + Inverter: Let’s say you have a large 400 amp-hour (Ah) lithium battery bank (gives about 5000 watt-hours of usable energy at 12V) and a 3000-watt inverter (with a 6000-watt surge rating).
- Can the inverter start the AC (2800 starting watts)? Yes, the 6000-watt surge rating is enough.
- Can the inverter run the AC (1400 running watts)? Yes, the 3000-watt running rating is enough.
- How long can the battery bank run the AC? If the AC uses 1400 watts continuously, that’s 1.4 kilowatt-hours (kWh) per hour. Your 5 kWh battery bank could theoretically run it for about 5 / 1.4 = 3.5 hours. But inverters use some power, and batteries are less efficient when drawing high power, so likely less (maybe 2-3 hours). This is why running standard AC on batteries for long periods is difficult and expensive.
-
12V Native AC (e.g., 8000 BTU): This type of AC might draw 80 amps at 12V when running.
- What is the power draw in watts? 80 amps * 12 volts = 960 watts.
- Can a 400 Ah battery bank run it? Using 960 watts is 0.96 kWh per hour. From a 5 kWh bank, potentially 5 / 0.96 = about 5.2 hours. Still drains batteries quickly, but much better than a standard AC. You need solar or another charging source to make this work for longer cooling times.
Other Things Affecting Power Use
Beyond the BTU rating and whether it’s starting or running, a few other things change how much power your RV AC uses:
- Outside Temperature: The hotter it is outside, the harder the AC has to work to cool the inside. Working harder means using a bit more power.
- RV Insulation and Shade: A well-insulated RV in the shade will stay cool more easily. The AC won’t need to run constantly. When it does run, it might use slightly less power as it is not struggling against a lot of heat coming in.
- Unit Age and Condition: Older AC units might be less efficient, meaning they use more power to produce the same amount of cooling. A unit that is not well-maintained (dirty filters or coils) will also use more power because it has to work harder.
- Compressor Type: Some newer ACs use “soft start” technology built-in (or you can add a soft starter). This greatly reduces the starting watts needed, making it much easier to run the AC on smaller generators or inverters.
Managing Your RV AC Power
Since the AC uses a lot of power, especially at startup, here are some tips for managing its use in your RV:
- Use a Soft Starter: Adding a device called a soft starter (like a Micro-Air EasyStart) to your standard RV AC unit can lower the starting watts by 60-70%. This is a game-changer. It allows many people to run a 13,500 BTU AC on a smaller 2200-watt generator or even on a 30 amp shore power service without tripping breakers when other things are on.
- Turn Off Other High-Power Appliances: If you are on 30 amp shore power or a generator and need to start your AC, turn off things like the microwave, coffee maker, electric water heater, or hair dryer first. Start the AC, let it run, then turn other things back on if you have power capacity.
- Cool the RV Before Peak Heat: If you know it will be a hot day, start cooling the RV in the morning when it’s cooler and the AC doesn’t have to work as hard.
- Improve Insulation and Shade: Keep blinds closed, use window covers, park in the shade if possible. This reduces the heat load on the AC.
- Use Fans: Ceiling fans or small electric fans help move the cool air around, making the RV feel cooler without needing the AC to run constantly on its highest setting.
How Many Watts Does An RV Air Conditioner Use? Summary Tables
Here are some tables summarizing the power use and what power source might be needed. Remember these are estimates.
Table 1: Typical RV AC Power Use (Estimates)
| BTU Rating | Running Watts | Starting Watts | Running Amps (@ 120V) | Common Shore Power Match |
|---|---|---|---|---|
| 13,500 | 1200 – 1500 | 2500 – 3000+ | 10 – 12.5 | 30 Amp or 50 Amp |
| 15,000 | 1500 – 1800 | 2800 – 3500+ | 12.5 – 15 | 30 Amp (careful) or 50 Amp |
| 12V Native AC (Lower BTU) | 600 – 1200 (@12V: 50-100A) | N/A (designed for low start) | N/A (Uses 12V DC) | Battery/Solar System |
Table 2: Generator Size Guide for RV AC (Estimates, consider soft starter)
| RV AC Unit | Recommended Generator Size (Running Watts / Surge Watts) | Notes |
|---|---|---|
| One 13,500 BTU | 2800 / 3300+ watts | 3000 or 3500 watt generators are common. Soft starter helps greatly. |
| One 15,000 BTU | 3000 / 3500+ watts | 3500 or 4000 watt generators are better. Soft starter recommended. |
| Two AC Units (e.g., two 13,500 BTU) | 5000 / 6000+ watts | Large generator or two smaller generators paralleled. Soft starters on both ACs help a lot. |
Note: Generator surge watts must be higher than the highest starting watts of any appliance you start on it, ideally with some room.
Table 3: Common RV Shore Power Capacity
| Service (Amps) | Voltage (V) | Total Watts Available | Suitable for Running |
|---|---|---|---|
| 30 | 120 | 3600 | One RV AC + limited other appliances |
| 50 | 120 x 2 | 12000 (split load) | One or Two RV ACs + many other appliances |
FAQ About RV AC Power
How many amps does an RV air conditioner pull?
An RV air conditioner pulls different amounts of amps. When it is running, a 13,500 BTU unit might pull 10-12.5 amps at 120 volts. A 15,000 BTU unit might pull 12.5-15 amps. When it first starts, the amperage (starting amps or LRA) is much higher, often 30-60 amps for a brief moment.
Can I run my RV air conditioner on batteries?
Running a standard 120V RV air conditioner on batteries alone is possible but hard to do for very long. It needs a very large battery bank and a strong inverter that can handle the AC’s running and starting watts. It drains batteries quickly. There are newer 12V native RV air conditioners that run directly on batteries and use less power overall, making battery power more practical for them, especially with solar panels.
How much power does a second RV air conditioner use?
A second RV air conditioner uses about the same amount of power as the first one, based on its BTU rating. If you have two 13,500 BTU units, you might need roughly 2400-3000 running watts total and face the challenge of starting both compressors (though usually you start them one at a time). This is why RVs with two ACs typically have 50 amp shore power service or need a large generator.
What size inverter do I need to run my RV AC?
If you want to run a standard 120V RV AC unit from batteries, you need an inverter that can handle both the running watts and the high starting watts. For a 13,500 BTU AC, you might need a 2000-watt continuous inverter with a surge rating of 3000-4000 watts or more. For a 15,000 BTU unit, you might need a 2500-watt or 3000-watt continuous inverter with a higher surge rating. A soft starter on the AC can lower the needed inverter surge capacity significantly. For a 12V native AC, you do not need a large inverter as it runs on DC power; you just need enough battery capacity.
Can I run my RV AC on a regular 15 or 20 amp house outlet?
You might be able to run a small RV AC or a low-power unit on a 15 or 20 amp house outlet, but it is often risky or impossible for standard rooftop ACs. A standard 13,500 or 15,000 BTU RV AC uses close to the total available watts from a 15A (1800W) or 20A (2400W) circuit just for running. The high starting watts will almost certainly trip a 15A or 20A breaker. You really need 30 amp or 50 amp service or a generator designed for RV use to reliably run a standard RV AC.
What is the difference between starting watts and running watts?
Starting watts is the brief, high amount of power an appliance like an air conditioner needs for just a moment to turn its motor (compressor) on. Running watts is the lower, steady amount of power the appliance uses continuously while it is operating normally. Starting watts are always higher than running watts for motors.
How long can I run my RV AC on a generator?
How long you can run your RV AC on a generator depends on the generator’s fuel tank size and how much fuel the AC and other loads cause the generator to use. A typical 3000-watt inverter generator might run a single RV AC for 6-10 hours on a tank of gas, but this changes a lot based on the generator model, the load on it, and how hot it is outside.
Does a dirty AC filter use more power?
Yes, a dirty air filter makes your RV AC work harder to pull air through. When the AC works harder, it uses more power. Keeping your filter clean helps the AC run better and use less electricity.
Knowing how many watts your RV air conditioner uses, both when starting and running, is important for having the right power source. Whether you use shore power, a generator, or try to use batteries, matching the power supply to the AC’s needs helps you stay cool and prevents problems.