If you’ve ever tried taking on a big DIY project, you’ve probably learned that there are two areas that are best left to the professionals: plumbing and electricity. If you don’t work with electricity on a regular basis and your years of high school physics are behind you, then you might not even remember how voltage, current, and power are all related to each other.
But fear not! When it comes to picking a generator for your RV there are three numbers you’ll have to know: volts, amps, and watts. We’ll go over what this means and what size generator you need to power your 30-amp RV.
Voltage is what electric charges move. Think of it as the ‘push’ that causes charges to move through a wire.
There are two things that you need to know about voltage in most RVs. First, your 12 volt (12V) battery will power some small things in your RV like basic lights, your water pump, and other small essentials. The rest— such as your appliances and outlets— will be powered by connecting your RV to shore power or a generator, which provides 120 volts (120V) of electricity.
Current is measured in amps, and it tells you how fast electricity flows through a system.
An RV with a 30A connection will only let electricity pass through it and into the RV at 30A, no faster and no slower.
Wattage is a measure of power, or the ability to get work done. That is electrical work, in a physics sense, so think of what it takes to power a refrigerator, or air conditioning, or TV. Each of these takes a set number of watts, and we will discuss how many they take below.
The simple formula connecting these three measurements is W=V*A. Since the electrical system of your RV will only run at 120V and 30A, the maximum power your RV can use at any given time is 3600 watts.
TYPES OF RV BATTERIES
Wondering what the difference is between a lead-acid battery and a gel mat battery? Learn more about the differences between battery types in this blog!
Here’s how many watts you can expect common RV appliances to use. Keep in mind that these are just general estimates. For more exact measures, refer to your RV or appliance owner’s manual.
This is a major power draw. Your air conditioning unit shouldn’t have to be running all the time if you have good insulation, but when it's burning hot outside, you might not have a choice.
You can expect the average RV air conditioning unit to use up around 2,000W when it starts up, and around 1,500W to keep it running according to RV Tech Library. This means that if you are turning on your A/C, you can only be using up 1,600W with your other appliances and electronics. While it’s running, you’ll only have 2,000W left over for the rest of your needs.
RECHARGING YOUR BATTERY
Don’t let a dead battery get you down. Read our guide to learn how to recharge your RV battery using a generator.
Here are some other power ratings for common RV appliances:
Small refrigerator: 500W to start and 300W to run, but bigger refrigerators can take up 800W
6-gallon water heater: 1,000W or more
TVs: 60W for a 30” LCD
Hand vacuums: 240W
If you plan on living in your RV full-time, you might want to look into a 50A model which has two 120V lines for a maximum of 12,000W. If you want to use the electronics in your 30A RV, you’re going to have to use them wisely in order to avoid putting strain on the system. Usually this means turning off one major appliance temporarily to use another one.
Overall, you should be fine with a 3,000W generator, or a 3,500W one on the safe side. Since the system is limited to 3,600W, buying a 4,000W generator may get everything you can out of your system, but you’re wasting 400W and burning fuel that you don’t need to.
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When shopping for a generator, this is one of the distinctions that comes up between listings.
While they both use an internal combustion engine to generate AC electrical power, how they do so is a little different. A conventional generator produces that energy by rotating at 3,600RPM to output 120V of electricity at 60hz. However, it is not a consistent 3,600RPM, so your electrical output is not going to be consistent, leading to dips and surges in power provided. This allows for some surge current, so you will find generators rated for, as an example, 3,000W of continuous power and up to 3,500W of power, which can be good for using big appliances like the air conditioning or fridge that use a lot of power starting up but level out once they’re running. The downside to this type of generator, unfortunately, is that there is always some fluctuation in power provided, which can be harmful to sensitive electronics such as computers, cameras, televisions, gaming consoles, and microcontrollers.
An inverter generator also uses an internal combustion engine to provide 120V of AC electricity at 60hz, but it then uses an alternator to convert it to DC. An inverter then converts the DC current back into AC current. While this may sound a little convoluted, it actually allows the generator to output a consistent flow of electricity to the RV, making it safe to use with sensitive equipment.
On top of that, by keeping the energy output consistent, inverter generators are actually more fuel efficient, so you can power your devices for a longer time without needing to refuel. If you’re out boondocking (that is RVing somewhere without any shore power) this can be a big deal since you might be far from any gas stations where you are and can only carry so many gas canisters with you to refill. You will have to pay more for an inverter generator over a conventional one, but you might end up saving money in the long run from the improved fuel efficiency.
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