What Size Generator For RV With 2 AC Units

Let’s be honest; most of us have wanted to stay in an RV at some point. It’s fun and exciting, making it perfect for vacations.

But to run several AC units in your RV, you’d need a powerful generator, and the last thing you’d want is your generator shutting down or not being powerful enough. So what size generator for RV with 2 AC units?

You’d generally need around a 5000-watt generator for 2 AC units for most RVs. Today I’ll be covering all about generators for RVs. So without further ado, let’s begin. 

How Many Watts Does a 13500 BTU RV AC Use? 

If you’re wondering what size generator to run 13,500 BTU air conditioner in your RV, the minimum is 3000 watts. However, it’s recommended to get a higher wattage. 

This is because the air conditioner takes at least 2800 watts to power up and then another 1800 watts to keep it running. If you have, for example, a 2500-watt generator,  your AC won’t power up. 

How Many Watts Does a 13500 BTU RV AC Use

But since a 3000-watt generator is a minimum, we’d highly recommend getting a higher power generator, preferably a 3200 or 3500-watt one. If it doesn’t fit your budget, you should consider getting a 13000 BTU RV AC instead.

This will only require about 2500 watts to start up and 1500 watts to keep running, so you’re fine with using a 2500-2800 watt generator. 

What Size Generator For a 50 AMP RV With 2 AC Units?

Unlike a 30-amp RV, a 50-amp power connection usually will have two separate feeds of 50-amp. This makes them use more power, but they’re able to do much more than regular ones. 

And to run 2 or 3 air conditioning units, you’ll need any generator between 7500-12500 wattage. But since most 50-amp RVs have a lot of electronics working at once, a 12000-13000 wattage supply is recommended. This will be plenty to run 2 AC units. 

But if you’re running one large AC unit, 4000-8000 watts will be enough depending on the air conditioner. For more than four units, you’ll need 15000 watts, and for five units, you’ll need 18000 watts. 

What Size Generator For a 50 AMP RV With 2 AC Units

You usually won’t need more than 2 units running at once anyway. So if you’re just running one air conditioner at a time, you won’t need any more than a 5000-6000 watts supply. Try to pick a generator with good portability and fuel efficiency too. 

Another thing to consider is silent generators. Try to find ones that don’t make noticeable noise. They’ll be slightly more expensive, but it’s worth it considering how disturbing the sound is. But if you want to find how much wattage you need exactly, here’s how —

How To Find Exact Necessary Wattage

Instead of winging it and hoping your generator is powerful enough for the 50-amp rig, we’d recommend calculating the required wattage instead, as it’s relatively easy.  You can do it with a RV generator calculator too.

But to calculate it manually, find out the maximum necessary wattage for all your appliances. Your essential appliances usually won’t need any more than 1200 watts. However, your air conditioner will usually require at least a 3000-watt generator to start up. 

As a general rule of thumb, you should get 500-1000 watts more than the maximum required wattage for your appliances. So for a 3000-watt air conditioner, get a 4000-watt generator. This will be enough to power everything in your RV. 

How To Find Exact Necessary Wattage

You should also consider how many appliances you use at the same time. For example, if there are two AC units running simultaneously, you’ll need at least 8000 watts on a 50-amp rig. 

But if you have many demanding appliances running at the same time, an 8000-12000 watt generator can be the best. 

Rv Generator Shuts Off When Ac Is On

There are tons of reasons your RV generator might shut down if your AC is on, so here’s a list of all the common ones —

Rv Generator Shuts Off When Ac Is On

Level Of Oil

The oil in your generator is one of the most vital parts to keep it running. As you use the generator, the oil will increasingly get lower and lower until it drops below the required level. If this happens, your generator will instantly shut off. 

Another probability is if the oil used in your generator is too old or your oil filter isn’t working. To fix this issue, replace the oil or the oil filter. Try to fill the tank halfway with oil as well. This will most likely get your generator running again when your AC is on. 


The carburetor or carb mixes the fuel and air to get the perfect fuel-air ratio on your generator. But while inserting oil, the carburetor can get clogged if done poorly. 


You can prevent this by frequently changing the oil. But if your carburetor does end up getting clogged, you need to drain all of the fuel and clean it thoroughly. If it still doesn’t fix the issue, try replacing it with a new one. 


As mentioned earlier, the filters of your generator can get dirty or clogged over a long period of time. This will prevent oil from entering the generator, or worse, dirty oil can pass through it. 

To prevent this, patch up any leakages and clean your clogged filter. If it still doesn’t fix the issue, put a new filter in your generator. You’d generally want your fuel to be above 1/4th of the tank to keep it working properly. 

Fuel Cap 

While your generator’s engine runs, a vent is used to insert air inside the generator to balance the oil levels. But if the vent is clogged due to a tight fuel cap, it can cause a vapor lock causing the generator to shut down. 

To check if it’s clogged, loosen the fuel cap and run your generator. Replace the fuel cap if it runs smoothly and doesn’t shut down. You shouldn’t bother trying to clean the fuel cap as it isn’t worth your time or effort, and it’s better to get it replaced.

Spark Plug & Battery

By now, your generator should stop shutting down while your AC is off. But if it doesn’t, you should check if the spark plugs make a spark when you turn the generator on. If it doesn’t, get it replaced. 

A poor battery can lead to your generator not turning on, so you should replace your battery if it still doesn’t work. 

Poor Maintenance

You should make sure to change the oil and filters of your generator frequently. This will prevent getting any issues while using it in the future. 

How Long Will RV AC Run On a Generator? How Do I Know That?

Generally, you can keep your AC running overnight on your generator. Most generators can keep multiple appliances running for 8-12 hours. But to calculate it, you have to divide the fuel capacity of your generator by the fuel consumption rate.

You can find both of these in the manual while buying the generator. You can also google for your specific generator model, if you lost the manual. And since your generator will keep running as long as it has clean filtered fuel, you should frequently change the oil.

How Long Will RV AC Run On a Generator

Can I Run AC Without Generator?

Although you can’t run an AC without a generator for a long time, you can certainly run an AC on battery power for 30-60 minutes, depending on the strength of your battery. 

On a 100 Ah lithium battery, a 15,000 BTU RV air conditioner can run for 30 minutes.

This means for a regular 13,500 BTU AC; you can easily run it for 1 hour or more. But then again, you won’t be able to use any other appliances in the meantime, so we’d highly recommend you get a generator anyway. 

But if you have several 100 Ah batteries, it can actually be a reliable source of power to run your air conditioner and other appliances, especially if they can be recharged through solar energy. 

Can I Run AC Without Generator

Four 100 Ah lithium batteries can last a 13,500 BTU RV AC for 5-6 hours, and 8 of them can run it for 8-10 hours, depending on how often you use your other appliances. 

But at that point, it’ll be cheaper to get a 5000-watt generator. 


Hopefully, now you have a good idea of what size generator for RV with 2 AC units. To recap, 5000 or 6000 watts will be plenty for 2 AC units. 

As a final tip, we’d highly recommend you to look into silent generators over powerful ones. You probably won’t need to run two air conditioners simultaneously, so a quiet 5000-watt generator will be enough.

A 6000-8000 wattage generator can do more than you can imagine. It can power multiple lights at once, including an air conditioner, fridge, and TV, even on a 50-amp 25-foot travel trailer. So it’s rarely necessary to get a 12,000-watt generator. 

But with all that being said, good luck picking your generator, and cheers!