One of the most significant differences between old-time camping and modern RVs is the installed electrical equipment. When folk used to go camping in the old days, nights were spent around a fire, and food was cooked in the same way. Although the modern RV owner can still have a fire, more options are available.
Most RV parks provide a “shore-based” power supply that fits every RV, and the RV owner can plug into it, and hey presto!! The RV has power. What if you are boondocking and have no access to mains electricity? Then, you need a correctly sized generator to provide the power.
Whether you like to travel or live in your RV, you need enough power to operate the essential appliances and other electronic devices that you rely on to navigate, communicate, or keep you entertained. If there is no main power, you’ll need the right size generator to power your essential equipment.
How To Size The Generator You Need For 30 Amp And 50 Amp RV’s
RVs are sold already equipped with 30amp or 50amp electrical systems. Before continuing, let’s quickly understand the implications of both numbers.
Amps measure the speed at which an electrical current passes a specific point. It represents the maximum electrical current that appliances can safely draw from it.
The amps which electrical appliances draw are cumulative, so for example, you have two devices on a circuit, and each draw 5 amps, the total amps being drawn will be 10amps.
The circuit breakers (trip switches) are measured in amps, and if the amperage exceeds the rated value of the breaker, it trips and “switches the system off.” This article discusses two circuits, one with a total amperage capability of 30 amps and 50 amps.
To calculate the amperage draw, divide the wattage (power) rating by the voltage (current strength) from the power source.
Before purchasing a generator, whether it can supply 30amps of power, or 50 amps of power, it is good to work out your requirements. Just because the maximum rating is 30 or 50 amps doesn’t necessarily mean that this is your actual need.
How To Measure Your RVs Electrical Draw
The electrical appliances draw two types of voltage in your RV. These are Alternating and Direct Current. The amps for DC and AC amps are the same things in that they are the measurement of electrons past a specific point; the difference is that with AC, the electrons go back and forth (alternating), and with DC, they only move in one direction (direct).
AC appliances such as air conditioners, microwaves, and fridges all use AC, whereas fluorescent lights, gas detectors, sound systems, and power roofs all use DC,
If you are plugged into an AC power source, the AC appliances draw the power directly from the source, whereas the DC appliances need the current to be first converted by the RV converter, which changes it to DC.
There are two methods to calculate your RV’s current draw.
Identify all the appliances which draw current and split these into two sections, namely AC and DC appliances. Check on the specification sheet of each device and jot down the amps for each unit.
The result will look something like this.
| 120 Volt AC Amp Ratings | |||
| Appliance | Estimated Amps | ||
| Air Conditioner | 12-16 Amps | ||
| Coffee Maker | 5-8 Amps | ||
| Computer (Laptop) | 2-3 Amps | ||
| RV Voltage Converter | 1-8 Amps | ||
| Electric Blanket | 0.5-1.5 Amps | ||
| Electric Fan | 1 Amp | ||
| Electric Water Heater | 9-13 Amps | ||
| Hair Dryer | 5-12 Amps | ||
| Iron | 5-10 Amps | ||
| Light (60 watts % 120V) | <1 Amp | ||
| Microwave | 8-13 Amps | ||
| Refrigerator in AC mode | 5-8 Amps | ||
| Television | 1.5-4 Amps | ||
| Toaster | 7-10 Amps | ||
| Washer/Dryer | 14-16Amps | ||
| 12 Volt DC Amp Ratings | |||
| Appliance or Accessory | Estimated Amps | ||
| CO Detector | 1 Amp | ||
| Fluorescent Light | 1-2 Amps | ||
| Furnace | 10-12 Amps | ||
| LP Gas Leak Detector | 1 Amp | ||
| Overhead lights (Per Bulb) | 1 Amp | ||
| Power Roof Vent | 1.5 Amps | ||
| Range Hood (Fan & Light) | 2-3 Amps | ||
| Refrigerator (LP Gas Mode) | 1.5- 2 Amps | ||
| Water Pump | 4 Amp | ||
Add up each section of the table, and you will arrive at the estimated amps required from both the AC and DC system.
An easier way to calculate the amps used by the DC system is to connect an ammeter between the battery’s negative terminal and the corresponding battery lead (which you will have first removed). Switch on the appliances and equipment that draw DC power and check the ammeter to read the amps used.
How To Size The RV Generator?
Sizing the generator is the easiest part of the whole exercise. Equipment that generates electricity uses watts to measure the electrical power produced.
To work out the watts, you multiply the voltage by the amps.
Assuming all the equipment on the above table is being used simultaneously (an unlikely event), then the total amps which are drawn by the appliances will be
Alternating current – 87 amps (using the minimum values)
Direct Current – 23 amps (using the minimum values)
Total amps – 100 amps
For this calculation, let’s assume that as not all appliances are switched on simultaneously, the system only needs to produce
35% of the total at any one time.
Using this example, we will only need a generator rated for 35 amps.
The watts requirement is ascertained by calculating the volts * amps.
If the system is geared around a 120volt current supply, then 120*35 equals 4550; this is the size of the generator which you will realistically require.
Although we have spent some time assessing what your actual draw may be, the title of this post is about the size generator required for a 30-amp and 50-amp RV system.
As discussed, we calculate the power (watts) of the required generator by multiplying the voltage by the amps; this results in the following maximum power capabilities of the generator.
30 amp – 120*30 = 3.60 kw
50 amp – 120*50 = 6.00 kw
The figures above are the maximum you require. Oversizing the generator is not a dangerous exercise, but it is pointless.
- Firstly, the higher the generator’s power rating (watts), the higher the price.
- The higher the generator’s power rating, the higher the gas consumption and therefore running costs of the unit.
- The generator only produces the power which the system requires.
As you will seldom use the RV system’s total capacity (which is why you should complete the exercise detailed above), a lower power-rated generator may be adequate.
Another factor you must consider is that a 30amp system has three wires, i.e., a 120-volt hot wire, a ground wire, and a neutral wire.
A 50amps system generally has four wires, namely 2*120volt hot wires, a ground wire, and a neutral wire.
The generators required for both systems are different from the calculation above.
30 amp – 120*30 = 3.60 kw
50 amp – (120*2 hot wires) *50 = 12.00 kw
And Then We Add An Air Conditioner Into The Mix
The most significant difficulty is attaching very high draw units to the system. An air conditioner is an excellent example as it adds an excessive draw.
Different sized air conditioners require higher power. Air conditioners also use a much higher watt level at startup, called the starting watts; even though it is only needed for seconds, the system must have sufficient capacity to start the unit.
The following table shows the power requirements at startup and ongoing running that the air conditioner needs.
| Recreational Vehicle AC | Watts Required for startup | Average wattage once running |
| 7000 BTU RV air conditioner | 1700 | 600 |
| 10,000 BTU RV air conditioner | 2000 | 700 |
| 13,500 BTU RV air conditioner | 2750 | 1250 |
| 15,000 BTU RV air conditioner | 3500 | 1500 |
To run a 13,500 RV air conditioner off a generator will require 2,750 at startup and 1,250 for the ongoing running. Remember, the startup rating is needed when you first switch the air conditioner on, and every time the thermostat registers, the compressor needs to turn on.
An air conditioner using 2.75 kW will draw 22.9 amps; this represents 76% of the RVs total circuit capacity
on a thirty amp circuit.
You must be aware that while the air conditioner is using a large part of the RVs system, you will need to switch other appliances off to make sure the system doesn’t trip.
What Are Important Features For An RV Generator?
The ideal RV generator may have a few different features to the one you use as a back at home.
The following section looks at the different features which you can consider.
What Fuel Does The RV Generator Use?
The three fuel types for generators are.
- Gas
- Propane
- Diesel
Some generators can use gas and propane as the primary and backup fuel sources; this is a worthwhile consideration if you are far away from civilization and can’t source gas (or propane). Because of the convenience this feature offers, it is recommended that you purchase a generator that caters to this.
The Power Output Must Be Adequate.
We have discussed this at length in the blog; suffice to say that you should specify a generator that produces sufficient but not excess power. As before, the following are the maximum rating of the generators you will need.
30 amp – 120*30 = 3.60kw
50 amp – (120*2 hot wires) *50 = 12.00kw
The Model Generator Must Be As Fuel-Efficient As Possible
Being fuel-efficient is an obvious but essential requirement. With the gas price continually rising, your wallet will be happier if less fuel is used.
The Generator Should Be A Quite Running Model
There is nothing worse than the continual drone of old-style generators which other RV owners use throughout the night. It makes sleep almost impossible and serves as a big damper on the overall enjoyment of the RV holiday.
For your and your neighbor’s sanity, we can’t emphasize the importance of buying the quietest generator possible.
The Generator Should Be Easy To Carry, Position, And Store
On behalf of every RV owner’s sore back, I urge you not to buy an enormous behemoth of a machine.
It probably has its own set of wheels; however, unless you have facilities for running it in-situ, you still must maneuver it outside of the compartment you stored it in so that it can be connected and not run in an enclosed space.
Moving a very heavy generator contained in an equally heavy frame is back-breaking work that you should try to avoid as far as possible.
How To Set Up An RV Generator
After purchasing your generator, it is time to set it up. Follow the steps below to brew your first cup of coffee as quickly as possible.
- Choose a place where the generator will have good air circulation (not inside an enclosed compartment in the RV unless specifically designed for this)
- Position the generator on a level surface.
- When you purchase the generator, it will have been supplied with a grounding pole and pole driver. Use the pole driver to drive the grounding pole into the ground as deep as it will go.
- Connect the supplied loop of copper wire to the grounding pole and the point on the generator it is designed to fit.
- Ensure the generator’s exhaust is not facing any of your (or your neighbors) windows.
- Fill it with fuel
- Check that the oil level is sufficient
- Plug the RV power cable into the generator (after making sure that it is connected to the RV as well!).
- Turn the key, and the starter motor will activate the generator and WALLA; you have electricity.
Conclusion
Whether you have a 30amp or 50amp power system in your RV, there is a generator that you can purchase to suit your needs. Don’t overspend on too much capacity because it is a waste, and make sure that you only run as many appliances as your RV system can handle at any time.
When you purchase a generator, make sure that it has a sufficient power rating, but also make sure that you specify that it must be portable and quiet.
Good luck, and happy camping!
Check out our article on: Best Portable Generators For Camping and RVs
