Saturday, December 9, 2023


What size RV generator do I need?

By Cheri Sicard
What size RV generator do I need?

After buying a used RV that is no longer produced and that came with no owner’s manuals, I knew this was a question I needed help with. And perhaps some of you do too, as I can’t be the only one in these circumstances.

One of our favorite RV YouTube channel hosts, Josh the RV Nerd, is here to help in the video below.

Even though this might seem like a straightforward question, it can sometimes get a little complicated.

Josh says that you can nerd out and do a lot of formulas and technical calculations. He will leave the actual calculations to you but the basic formula is:

Amps X Volts = Watts

Josh says he has an easier way without nerding out on math, and in the video, he shows his 3-point process. For general camping, Josh says his method will work about 99% of the time.

In a nutshell, you will need to match the rated output of the generator against your expected power usage.

A lot of people like to calculate (or estimate) a worst-case scenario. In other words, how much power would I need to turn on everything all at once?

When I heard this, my first reaction was, heck no! I won’t do that as the ONLY time I ever need a generator is to run my A/C, and that is the only thing I need the generator to do. My solar power stations and house batteries can easily handle my other needs.

And it turns out I was ahead of our esteemed host as he talks about just this scenario.

Likewise, you should estimate your power usage needs based on what is realistic for you, the appliances you use, and the way that you like to RV.

Most things in your RV sip (as opposed to guzzle) power, according to Josh. But in addition to the air conditioner, which we know draws a lot of power, if you regularly use any of these items, it will add to the amount you will need. As you can see, basically anything that heats takes power:

  • Microwave
  • Blow dryer
  • Electric coffee pot
  • Curling iron

If you don’t use any of these kinds of appliances, including the air conditioner, Josh says you might be able to get by with a small 2000-watt generator.

What if you just want to run an air conditioner?

I was happy that Josh ended up answering my exact question of what if I need to just run the air conditioner?

Josh says for a single 13,500 BTU air conditioner, a 3,000-watt generator will run most A/Cs. Barely. And the generator may struggle. It definitely won’t give you a full 30-amp service.

Josh says you can get around this by using a Hard Start Kit. I have always heard this called a Soft Start Kit and, as you know, we’re big fans of those at This kit helps give extra power at the A/C’s start-up, when the most power usage occurs.

Once your AC is up and running on the 3,000-watt generator you should be fine, Provided you are not using other appliances.

What about a 3,500-watt generator?

Josh says these are basically a 3,000-watt generator with a small boost kit added. Most true generators jump from 3,000 watt to 4,500 watt.

A 4500-watt generator will provide normal function to most RVs as long as EVERYTHING is not on at the same time. The downside? They are larger, heavier, and more expensive.

A better way

If you don’t want to struggle with lifting a huge generator in and out of your truck, there is a better way.

You can get two 2,000-watt generators, hook them together, and have the power of the larger 4,000-watt generator.

I know for me, this will be the way to go as I often camp alone. I can easily move a 2,000-watt generator. Four thousand, not so much.

The other advantage is, you can leave one at home if you are traveling at a time of year when you won’t need the A/C.

What size generator do I need for larger RVs or those with more than one A/C?

For these, Josh says you are best off with a big 5,500-watt generator. These are often built into the RV, but if you have to get a portable generator of this size, be warned that they are both large and heavy.

Before he signs off, Josh does put in the caveat that the advice he is giving will work for 99% of scenarios. That said, he is not a trained generator specialist. So if you are in doubt, or you have particular or special needs, you might want to seek out someone who is.



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Neal Davis (@guest_240110)
5 months ago

Our generator came with the rig, but I wish that I at least had inquired about changing it out for a larger one. Thank you, Cheri!

Bob P (@guest_240014)
5 months ago

I bought a 4500W Pulsar inverter generator which will run everything in the camper. Then I found that the trailer manufacturer decided to put all the electrical outlets on one 20A circuit breaker, bathroom, living room, kitchen, and bedroom figuring there probably wouldn’t be more than 2-3 outlets being used at any one time. Little did they know DW would plug in the electric skillet, coffee maker, portable space heater to take the chill off all at the same time. The generator labored under the load for maybe 2 seconds before the circuit breaker tripped. That’s when I found that all the electrical outlets were on one 20A breaker. I wouldn’t have needed that big of a generator had I known this ahead of time a 2000W would’ve sufficed as long as I didn’t need A/C also.

Thomas D (@guest_240098)
5 months ago
Reply to  Bob P

Listen up! Circuit breakers and gfci outlets cost money.
We can’t afford to have more curcuits. And labor costs money. Put in one circuit and we’ll call it good. ( NEVER say good enough, means it could be better)
The bean counters!

Justin Moore (@guest_239937)
5 months ago

Just picked up last night a Predator 3500 from Harbor Freight with my 25% off coupon. If you get a no exclusions coupon it can’t be beat.

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