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What Size Generator do I Need for a 30-amp RV?


In general, a 30-amp service generator should be sized at around 3,600 watts (which is the maximum that this service allows), on the other hand, you have to consider the high altitude areas and hot weather situations, where power can be lost. You can either get one 3,000-4,000 watt or two smaller-sized inverter-generators and parallel them together. This will give you the flexibility of having more power when needed and less when it is not necessary (which will result in fuel savings due to no energy waste).

With this setup, you will be able to use only one of the generators for smaller devices (like electronics) and double the power by paralleling to use an air conditioner in summer (for example). Two stand-alone inverter generators are an excellent option if want to have more power, but don’t need it all the time.

The common size of the generator for 30-amp service is usually no more than what your RV is wired for:

30-amps x 120 volts = 3,600-watts

The rest – is your personal setup preference (maybe lifting two 45-pound generators than one 100-pound generator works out better for you) or your traveling needs (high altitude and really hot destinations). Also, you may want to add a soft starter to your setup or use an inverter charger with a power-assist mode to compensate for using a smaller-size generator.

Most inverter generators have paralleling capability, but they do require a connection cable with a receptacle. Parallel connections vary and there is a variety of power outlets that come in your paralleling kit (which is very often has to be purchased separately).

Here is an overview of different inverters and their paralleling connections:

Not to mention, smaller-sized generators are relatively light and are easier to move around. After calculating your wattage needs (add all the devices that will be used at exactly the same time and go with the highest number), just give yourself a room of about 20% and this will be your generator size.

Another factor to consider if you are planning to get a bigger-sized (one-only) generator is where you are going to put it. As you can imagine, it is much easier to find a perfect spot for a smaller generator, even if you have two of them. This type of setup is perfect for those who boondock a lot.

And guess what happens if one of the generators breaks down in the middle of nowhere? You will still have another one to fall back on for basic necessities…

It’s important to note that:

Different brands have different guidelines to what kind of generators can be paralleled.

Some only allow the same exact model and size to be paralleled, while others are more flexible and allow you to parallel different brands of the same size or different sizes of the same brand and family. Check with your generator manufacturer.

Also, not all generators can be paralleled. You can parallel the following generators (paid links below):

  • Honda EU2200i – higher-end pricing, 2200 starting watts /1800 running watts, up to 8.1 hours of runtime @ 25% load.
  • YAMAHA EF2000iSv2 – higher-end pricing, 2000 starting watts /1600 running watts, up to 10.5 hours of runtime @ 25% load.
  • Champion 2000w – reasonably priced, 2000 starting watts /1700 running watts, up to 11.5 hours of runtime @ 25% load.
  • WEN 56200i 2000w – reasonably priced, 2000 starting watts /1600 running watts, up to 9.4 hours of runtime @ 25% load.
  • Westinghouse iGen2200 – 2200 starting watts /1800 running watts, up to 12 hours of runtime @ 25% load. Different-size models can be paralleled with this generator, which means that you can have a bigger and a smaller one.

Parallel kits are all sold separately.

Sizing for altitude and temperature

Altitude problems

Since really never know where your camping will take you (which is a good thing ????), if you end up in high-altitude areas and would like to use your generator, you may notice that power output will drop (about 3% – 3.5%  per 1000 feet).

Having less oxygen in the air is what causes problems with generators. If fuel doesn’t burn properly, you will not get as much power out of it as you would otherwise. This is normal and should be added to your calculations if you are really traveling a lot.

Image source

So, let’s calculate what happens to the wattage of a 3,500-watt generator at high elevations:

Elevation Power loss
Adjusted wattage
1,000′ 3.5% 3,378-watts
2,000′ 7% 3,255-watts
3,000′ 10.5% 3,132-watts
4,000′ 14% 3,010-watts
5,000′ 17.5% 2,887-watts

** Note. These numbers are approximate calculations, consult the manufacturer for details.

When buying a generator, make sure you MATCH the running wattage rating to your needs, and NOT surge watts (in many cases, it is not always obvious):

“Surge-watts” is NOT a continuous power and it will only last for a few seconds. On the other hand, you should watch the SURGE rating to make sure it will be able to power your high startup surge equipment or A/C.

If you look at your generator’s owner’s manual, you will find recommendations for operation in high-altitude areas. The popping sound is usually an indication that your generator is running too lean.

To solve this problem, manufacturers created a special carburetor kit with high-altitude jets that need to be installed in certain altitudes for your generator to run safely. It is also highly likely that generators with adjusted jets (that this kit supplies with) will still experience decreased performance in altitudes above 7000′.

Drawbacks to these kits are:

  1. You will need to use genuine parts from the manufacturer because otherwise, you will probably lose your warranty.
  2. You should change your carburetor back to normal once you leave a high-altitude place. It is DANGEROUS to use this setup on lower altitudes and you are risking motor overheating or even blowing up…

Image source

Here is a good video on testing various generators at different altitudes:

If you don’t permanently live in high-altitude areas, it is much easier to account for power loss and get a larger generator than to make generator adjustments. Only make sure that your manufacturer will not void your warranty in this case.

On the other hand, if this is where you are parked most of the time, larger generators will allow you to keep it under 80% load, which will maximize its lifespan.

You may also find using a propane gas (LPG) more convenient in high altitudes, but it has the same effect since the air is still thin. If they stop working completely, you can try opening the air intake port slightly more than the factory setting.

High-temperature problems

As you see from the picture above, the power output of the generator can decrease by about 1% for each 10 degrees F (above 60 degrees F ambient temperature). This is another reason why you may want to slightly oversize your generator if you live or travel in hot weather areas.

Sizing for smaller generators

If you do NOT want to buy a large generator (or two smaller ones), you do have some other options. First of all, you will need to make sure your appliances that can run on propane are ACTUALLY USING IT!

If you have a 2-way or a 3-way refrigerator (that can run on propane), turn them manually to the propane setting, because they are programmed to work on 120-volt electricity first and propane second and will NOT do so automatically. Other options include:

  1. Using a soft starter for large appliances (like A/C).
  2. Using inverter-charger with power-assist mode (a good battery bank will be needed as well).

Soft starters

If wasting fuel is not your primary concern, you may still get away with using one smaller-sized generator (that matches your load, of course) to get your A/C going if you use a soft starter. The reason for this is that air conditioners don’t really require high wattage to run on, the problem is a STARTUP SURGE!

It gets installed on your A/C and its whole purpose is to reduce the torque applied to an electric motor during startup or anytime the compressor kicks in. This is a good solution if you want to run your rooftop air conditioner, but don’t have enough surge watts to accommodate it.

So if you want to have a small-sized generator and still power your A/C, this awesome device can really pull it off! Here is a popular model among RVers from Soft Start RV (paid link):

Check it out! You will not be sorry. Only make sure that your generator actually has enough RUNNING watts for your A/C and other appliances (that you may want to use at the same time).

Power assist mode

You can also get away with using a smaller-sized generator by installing an inverter-charger with power assist mode and investing in a good set of lithium-ion deep-cycle batteries. The inverter charger should also be sized to your 30-amp service if you ever want to use it to its full capacity (without a generator) in the future.

For most people, a 3000-watt inverter-charger with power assist mode is sufficient to run alongside another power source (like a generator). This setup will allow you to run at full 30-amp power with a smaller generator and a battery bank as a power source.

My recommended brand is Victron, which was tested by many RVers and is capable of different customization options. You can set it to start utilizing battery power above 12 amps (for example). Since generators have a tendency to lose their efficiency when running at maximum throttle, this setting will prevent them from running at full power.

If you think this will be a good solution for your situation, here is Victron Energy MultiPlus 3000VA (paid link) inverter charger:

Did I mention that it also produces a pure sine wave (which is great for your electronics)? Investing in an inverter-charger like this may be a good solution if you are frequently traveling to high-altitude areas and need a way not to use your generator at all!

Instead of worrying about a generator, you can simply use your battery bank.

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Attention! This article is for informational purposes ONLY and is NOT a replacement for professional advice! ALWAYS consult your local specialist for an appropriate solution to your problem. All statements, prices, contact information, recommendations, and reviews contained herein came from sources that we believe to be reliable, but the accuracy or completeness thereof is not guaranteed. Please contact the service provider for complete details and updates.

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