By Cheri Sicard
Question: “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 when I received this question that I would need some help answering it. And perhaps some of you would, too, as I can’t be the only one in these circumstances.
One of our favorite RV YouTube channel hosts, Josh the RV Nerd (now at Bish’s RV), offers help in the video near the bottom of this article.
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.
Therefore, 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 about what would I need to just run my air conditioner?
Josh says for a single 13,500 BTU air conditioner, a 3,000-watt generator will do most often. Barely. But 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 RVtravel.com. This kit helps give extra power at the A/C’s start-up, when the most power usage occurs.
Once your A/C 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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RVDT2736
“Hard start” and “soft start” kits are not the same thing. In fact, they’re pretty much opposites.
A hard start kit provides extra starting power to the compressor, to start it as quickly as possible. This reduces the startup time and the wear on the compressor. They’re typically used in commercial or larger residential A/C systems.
A soft starter gradually starts the compressor in order to minimize the amount of power draw on startup. It allows A/C units to run on generators or inverters that can’t handle the unit’s standard power draw. That’s why we use them in RVs.
I’ve read that soft starters can potentially reduce the life of the compressor, but I don’t know if that’s actually been an issue in RV applications. The new generation of RV A/C units with variable-speed compressors eliminates the need for soft starters.
I installed my SoftStart over 3 years ago and my 15k Coleman Mach is still running fine. I have heard the opposite…the SoftStart will prolong the life of the compressor and so far that has been the case.
I switched from a 3500 Watt, 100 pound Predator to a 4500 Watt, 50 pound generator about 6 months ago. It is Dual Fuel so it runs on propane as well. My AC is a 15k with a SoftStart and it ran just fine with the 3500 Watt Predator. The main reason I made the switch was the weight. https://www.championpowerequipment.com/product/201531-4500w-dual-fuel-inverter-with-co-shield/
Champion says it weighs 99.2 LB.
The Specs say 51.8 pounds. I can carry mine with one hand.
https://www.championpowerequipment.com/product/201531-4500w-dual-fuel-inverter-with-co-shield/#specs
I read that too. It might have been the one with electric start.
This is the one that weighs 92 pounds and has electric start:
https://www.championpowerequipment.com/product/201278-4500w-electric-start-dual-fuel-inverter/#specs
This is the one I have:
https://www.championpowerequipment.com/product/201531-4500w-dual-fuel-inverter-with-co-shield/
My biggest concern is a dead house battery. I carry a lightweight (about 40 pound) 15A+ dual fuel sinewave inverter generator – as I ONLY run it on propane, it can be stored under the bed. It can either directly charge the battery or I can hook it up via adapter & a ground rod to the shore power cable. With 12v, furnace, frig, water pump, lights all work and I can recharge phones or run a fan. Not all at the same time, of course. I don’t boondock by design, but prepared to do so temporarily.
P.S. I also have a power meter to go between the generator and the shore power cable, just to make sure I am not trying to pull too much off the generator.
I had a little Honda generator that would put out about 360 watts. It’s all I needed overnight to keep the battery charged so the furnace didn’t quit at 5 in the morning. The gas tank was 1 litre (1/4 gallon) and it would run for 6 hours. I could carry it with 2 fingers and you could carry on a conversation next to it when running. I’m sorry I sold it.
I do the same with a honda 1000
K.I.S.S. formula = If you have a 30 Amp RV with a 15K (or smaller) A/C, install a soft-start device on it, bite the bullet, and get the Honda 2200i generator. Mine runs nicely even with the ECO Throttle on. Only concession is to shut off the A/C for the few minutes when using the microwave. The Honda is expensive but, it’s light at 47LBS, it’s the quietest of the bunch, has the largest engine, and they’re bulletproof. You really do get what you pay for.
Thank you for highlighting and summarizing the video, Cheri! Good advice to not just go buy something until some thought is put into how it will be used. Have a great day and safe travels!