So you want to know how many apps your RV or camper appliances draw?
Scroll down for a short n’ sweet guide to the inner workings of an RV electrical system. And how to calculate how many amps your RV uses yourself. (Hint: You’ll need a watt-meter!)
And a little further are two complete tables for 120V and 12V amp draw!
Table of Contents
Basics of RV Power Usage
Almost all RVs are powered by either a 30-amp 120-volt* service or 50-amp 240-volt service
A converter then transforms some of the 120-volt electricity to 12-volt electricity. The converter is the heart of your RV’s electrical system.
Some RVs also have an inverter, which works in the opposite direction: Turning 12-volt DC electricity into 120-volt AC electricity.
Actually, I pretty much wrote an entire compendium about the humble RV converter here.
You may see this referred to as 110, 115, 120, or even 125 volt service! For our purposes, they all mean the same thing.
Common 240-volt appliances are:
- Electric oven
These appliances are typically reserved for luxury fifth-wheels and motorhomes. Again, they require 50-amp, 240-volt hookup in order to function.
Common 120-volt appliances are:
- Air conditioner
Theoretically, 120-volt appliances can be powered from a 12-volt battery using an inverter. However, this consumes an incredible amount of power, so it’s rarely practical. Read my article here on why you (probably) can’t run your A/C on battery power.
Common 12-volt loads are:
- Water pump
- 12V television
- Ceiling fans
- Stereo head
- Slide-out motors
Many other smaller items, like CO2 detectors and lighted door handles, also run on 12V DC power. This electricity is supplied directly by the house batteries or through the converter.
Other appliances, namely the furnace and refrigerator, are designed to run best when using propane, but several models can switch to AC electric operation when hooked up to campground service.
Some components, such as a 3-way absorption fridge or AC/DC compressor refrigerator, can run strictly off 12V DC power! But be warned: “DC mode” consumes an enormous amount of power in a very short time. It is not practical for most RVers.
If you want to know more (or everything) about RV batteries and how they power RV appliances, check out my ultimate battery guide here.
Also, you should know that many appliances, such as an absorption refrigerator, propane stovetop or furnace, still require some 12V power to operate control electronics, temperature-sensing fans, etc.
How Much Power Do My RV Appliances Use?
*Beware: Math Ahead!*
Before you examine the tables, however, you should understand that amps do not equal power!
This is because of Ohm’s Law: Watts = Volts x Amps
W = V*A
Watts measure power. Amps measure current. To supply a steady amount of power, as voltage decreases, amps must increase!
A 1500-watt space heater will consume 1500 watts of power no matter how you run it (theoretically, anyway). Power is power!
- At 120 volts, that’s 12.5 amps.
- At 12 volts, that’s 125 amps! Yeesh!
So switching from “shore power” to “battery power” increases amp draw by 10x!
Even though it’s not technically accurate, a lot of RVers remember this by distinguishing “DC” amps and “AC” amps.
Here’s the rough math: If you need to convert AC to DC amps, multiply by 10. If you need to convert DC amps to AC amps, divide by 10.
If a 3-speed ceiling fan draws 3.1 amps on High, that’s “DC” amps! In other words, it will consume 3.1 amps, per hour, from the 12-volt battery.
However, if you remove the battery from the system, and you run the ceiling fan on converted electricity from the campground power supply, you’d only be consuming 0.31 “AC” amps!*
*Technically, you’d actually be consuming more, because converters aren’t 100% efficient, but let’s ignore that for now.
Anyway, here’s my table for amp draw for 120-volt appliances. You can filter and sort! Make good use of it!
RV Appliance Amp Draw: 120VAC
120V Load RV Amp Draw Table
|Appliance||Running Watts, Avg||Amps (@115V)||Notes|
|Air Conditioner 13.5k BTU, Cooling Mode||1250||10.9||High-efficiency units ~15-25% less power draw. Starting watts 2x!|
|Air Conditioner 15k BTU, Cooling Mode||1500||13.0||High-efficiency units ~15-25% less power draw. Starting watts 2x!|
|Window Air Conditioner, 5k BTU||500||4.3||Starting watts 2x!|
|Absorption Refrigerator, AC Operation||300-575||2.5-5.0||If icemaker, 2x! Starting watts 2x-3x!|
|6-gallon Water Heater, AC Operation||1400||12.2||~0 AC power used when on LP mode|
|DC Converter/Charger||0-1500||0-8/13||Based on your 12V loads and battery state of charge! Smaller converters max out 750-100W|
|Ceramic Space Heater, 1500W||1500||13.0|
|Oscillating/Box Fan||50-150||0.4-1.3||The smaller and slower the fan, the less power drawn.|
|Laptop Computer||50-150||0.4-1.3||Gaming, video draws more power.|
|Smartphone||2-6||0.02-0.05||Your smartphone has more computing power than Apollo 11!|
|Xbox / Game Console||65-180||0.6-1.6|
|Coffee Maker, Heating Up||1300-1500||11.3-13.0||Maybe consider a drip cone?|
|Coffee Maker, Keeping Warm||200-400||1.7-3.5|
|Blender||200-1000||1.7-8.7||Low power is harder on the motor!|
|Induction Cooktop (7-inch)||1200-1800||10.4-15.6|
|Microwave 900-1000W||1200-1500||10.4-13.0||At 100% power.|
|Microwave 1450W (Convection)||1450||12.6||At 100% power.|
|Microwave 1450W||1450||12.6||At 100% power.|
|Electric Heating Blanket||50-225||0.5-2.0|
|Battery Charger, 15A||1700||15||Output efficiency usually 80-85%|
|Drill, 5A||575||5.0||Get a cordless drill, you Neanderthal!|
P.S. Lest you become confused … I calculated the amp draw based on a line voltage of 115V. As a rule, the farther away from the electrical service entrance, the lower your line voltage (due to resistance losses).
In most campgrounds, you won’t get the full 120 volts … you’ll probably get 110-115.
And remember! As the voltage decreases, the amp draw increases! One balances the other to supply a constant amount of power! So the lower the line voltage, the more likely you are to overload or overheat a circuit. If your surge protector or voltmeter shows less than 108-110 volts at the site plug in, go somewhere else. Be safe!
… wait, you don’t have a surge protector? What, do you also run the bulls and BASE jump and try to deep-fry your own turkey? Are you crazy?? Learn about why (and what) you need for a surge protector here.
RV Appliance Amp Draw: 12VDC
12V Load RV Amp Draw Table
|Fluorescent Light||10-30||0.9-2.0||Not recommended for RVs|
|Furnace 16k BTU (LP Mode)||45-60||3.4-4.3|
|Furnace 25k BTU||100||7.5|
|Water Pump||50-110||4-8||Only while running|
|Absorption Fridge, DC Mode||180-275||14-20|
|Absorption Fridge, LP Mode||15-20||1.5|
|12V Stereo Head||7-50||0.5-3.5||Depends on speaker zone and volume|
|12V Outlet, Socket||120-130||10||Max charge rate|
|12V Outlet, USB||25||2.1||Max charge rate|
|AC/DC RV Fridge||50-180||4-13.5||Varies widely by make and model!|
|AC/DC Fridge/Freezer, Portable||8-30||0.7-2.3||Incredibly efficient!|
P.S. Again, lest you become even more confused … I calculated the amp draw based on circuit voltage at 13.6. That’s above the voltage of fully charged battery, but it’s roughly equivalent to the output of a running converter.
In actuality, voltage might drop as low 11.5 volts before you discover your battery is “dead.” Amp draw will increase correspondingly.
That’s the long way of saying actual amp draw could be 10-20% greater than what’s shown here.
How to Actually Measure Your RV Appliance Amp Draw
If you want to know the actual power draw for your particular appliance, you can do two things:
Look at the electrical requirements sticker information on the part, or search for the product listing page online. Most listed appliances will specify the input wattage to the part.
Better yet, measure it yourself. Get a plug n’ play watt meter, like this one here, and find out exactly how much power your appliance is using!
Seriously … I cannot recommend this enough. GET A WATT METER! The Kill-A-Watt is my favorite. You can check out the Kill-A-Watt meter here on Amazon.
Here’s how this plays out in reality. Most RVers have one of two questions:
- How many appliances can I run at one time?
- How long can I run my RV off my battery?
Let’s consider both questions.
- Psst . . . if you’re reading this content anywhere besides Ask The RV Engineer, it’s been illegally “scraped,” and you’re probably on a spam website. So please be careful! Don’t share any private information, and come back to us at www.askthervengineer.com!
How Many Appliances Can I Run At One Time in My RV Camper?
Usually, at a developed campground, you can either plug into 30A or 50A service.
When hooked up, there is no need to conserve power. The grid won’t run out. But if you run too many appliances at one time, you could overload a circuit and trip a breaker!
Some people will tell you that you need to measure or calculate the amp draw of every single one of your appliances and loads.
This is a massive waste of time.
As you can see in my chart, things like laptop computers, LED lights, televisions and oscillating fans simply don’t use that much power.
In fact, you really only need to consider three things:
- Appliances that make heat
- Appliances that cool (aka air conditioners)
- Appliances that move stuff (aka, with motors).
Let’s call these M3 appliances.
As you can see, electric water heaters, hair dryers, microwaves, electric refrigerators, coffee makers and space heaters all consume A LOT of power!
And while they don’t run for long periods of time, electric motors for awning extensions, automatic stabilizers, and slide-outs can demand a huge inrush of current!
So do portable, window and roof mount air conditioners. If you want to learn which RV rooftop air conditioners are the most energy-efficient, click here.
Here are three useful rules of thumb:
- Assume you can only run one (1) M3 appliance per circuit.
- Assume you can only run two to three (2-3) M3 appliances on 30A power and three to four (3-4) on 50A power.
- If you’re running a generator, assume you can run one (1) 2M appliance per 1500-2000 running watts.*
… and here’s my last caveat. M3 appliances with a motor – such as a fridge, A/C, or slide-out motor – often demand lots of energy upon startup (often 2-3x their running watts).
We engineers call these “inductive” loads rather than “resistance” loads.
Therefore, the startup demands of an air conditioner can easily overload a circuit. This is one reason I recommend a soft-start for your RV A/C!
How to Fix an Overloaded Circuit
All your 120-volt circuits run through your main breaker panel, probably located inside your converter/charger/power center.
These circuit breaker switches will flip when overloaded. Just flip the breaker switch to reset the circuit.
However, usually, the 12-volt circuits are protected with fuses, not circuit breakers. If a 12-volt circuit is overloaded, the fuse will blow. You’ll need to replace the fuse with the same size and type. Some converters have LED indicator lights to indicate which fuse is ruined.
How Long Can I Run My RV Off Battery?
So, actually, I already wrote an article series about this!
Here’s the synopsis:
Most RVs are designed to be operated while hooked up to a campground power supply.
If you’re boondocking solely on battery power, you probably won’t last long. And you can’t run your air conditioner or microwave.
Even with careful and conservative use, you’ll run down your battery in a day or two with the necessary demands from the lights, water pump, ceiling fans, etc.
- In fact, I answered this question (and many others) on my ultimate FAQ guide to RV deep-cycle batteries here.
- You have two basic options: Invest in a generator, or upgrade your battery bank and solar power system.
- I polled the public on this very option. Here’s an article about what people prefer: gas generator vs solar power?