RV Electricity Explained

Electricity in your RV

New RV'ers are excited about getting their new RV and anxious to get out and use it. Sometimes things work and sometimes they don't. Unlike normal homes electricity in an RV can be very different. And unlike living in a "stick & brick" you have to understand more about electricity.

RV's have two distinctly different electrical systems. One is the 12 volt DC system and the other is an AC system that operates on 120 volts AC supplied by either a 50 amp connection, 30 amp connection or possibly only a 15 amp or 20 amp connection. Of course a generator can supply this AC power as well.

Stick & Brick houses are constructed so that, for the most part, no one ever thinks about the electricity they are using. They just plug it in without thinking.

You are going to have to "think" in an RV. You may not want to but you are going to have to understand the difference between a 30-amp connection and a 50-amp connection. Once you understand that you will probably even need to understand a 15-amp or 20-amp connection.

In addition you will need to understand that some things run on 12-volts and if you don't have 12-volts those things won't work, like your refrigerator, water heater and propane heater to name a few. If you just breezed over that last sentence you need to reread it and contemplate exactly what it says and means. Without 12 volts to power the circuit boards your propane heater, water heater and refrigerator will not function. Additionally, 12 volts may be powering your CO detector (you do have a functioning CO detector don't you).

And while you are at it you best learn the difference between your house batteries and your chassis battery. In addition you had better understand how your house batteries and chassis batteries are recharged.

You do not need an inverter in your home but you do in an RV. You will need to understand what an inverter is and what it can do for you as well as what it can't do for you.

Converters and battery chargers are another piece of electronic equipment that you don't have on your automobile or in your home. However, you best understand the function of your converter and battery charger because they are essential items in your RV.

You may not want to know anything about electricity. You may just want to plug things in and have them work. I assure you it will not work that way.

It is hard to know where to start when explaining electrical systems in RV's since there is so much to discuss. However, a good place to start is to understand that RV's are designed to move from campground to campground or to even provide a place to live where there may not be any connections to utilities. It is these changing circumstances that make it mandatory for RV'ers to understand more about their electricity consumption and needs.

If you have just purchased a new motorhome or 5th wheel that has a 50-amp plug you have enough "toys" on board to consume in excess of 30-amps. If you are in a campground that has 50-amp connections then you can to operate all of your "toys" possibly all of them at the same time.

However, if you are in a campground that only has 30-amp connections then you are NOT going to be able to operate all of your toys at the same time because you will pull more than 30-amps and the circuit breaker supplying your 30-amps will pop. This is when you are going to have to understand how much "power" each appliance is consuming. Appliances have wattage ratings and usually an amperage rating. You need to know how much power (watts/amps) each appliance is using.

We happen to have a motorhome with a 50-amp power cord. Sometimes we are in a campground that only supplies 30-amp connections. When we are in these campgrounds we can not run both of our air conditioners ------- even if it is hot. Our two roof air conditioners pull about 15-amps each. Well, you say 15 and 15 are 30 and you would be correct. In theory if those air conditioners were the only thing drawing current we may be able to run both of them. However, when we connect to shore power (that 30-amp supply) in a campground I know that my inverter/converter/battery charger will take some of that 30-amps---- possibly 5 to 10 amps depending on what the load is. When I plug into shore power the refrigerator will switch from natural gas to 120-volts. That could draw another 5-10 amps. We will probably have lights on in the motorhome drawing more amps. If the TV, DVD, VCR, microwave, toaster oven, hairdryer, coffee maker, computer etc., are on they will be drawing some of that 30-amps. Needless to say you are going to be able to only run one air conditioner when you have a 30-amp connection because of all the other things that will need power.

Now I am hoping that you are beginning to understand better. Things like air conditioners, microwaves, toaster ovens, electric heaters and hair dryers draw a lot of amps as in 12 to 15-amps each. You can't run more than 2 of those items at one time if you only have a 30-amp supply. You don't even think about this at your "stick and brick" but you will have to in your motorhome.

Things like clocks, electric toothbrushes, and electric shavers don't consume much of your amps. Your TV, DVD, VCR and computer consume a bit more but still aren't hogs.

Overhead lights can be 12-volt or 120-volt. They will add up but are like your TV, DVD and VCR. They aren't the big power consumers.

Hopefully, by now you have realized that you will need to manage your usage of appliances when you have less than 50-amps available.

If you spend much time in your RV you will eventually stay in a relative or friends driveway for a few days. When you do this you will probably only have access to 15-amps or 20-amps if you are lucky. That is OK, you can get along just fine if it isn't hot where you will need air conditioning.

We can get by just fine on a 15-amp connection for weeks at a time. To do this we have to "manage" our electricity consumption. We can run the microwave or the toaster oven but not both. Joyce can operate her hair dryer provided we are not using another high draw appliance. The key to us getting by with only 15-amps is knowing what each appliance draws and not exceeding the 15-amps.

You never know when you are going to be staying in a place with only 15-amps so be prepared. When we are in South Florida in the winter we have a park we like to stay in because they have "overflow" sites for $15 a night. That is CHEAP in South Florida in the winter when most places are $45 and up a night. We are just fine in one of those "overflow" sites with water and a 15-amp connection. It keeps the batteries charged and provides us with everything we need.

Over the years we have spent the night at a variety of "mechanics" shops. Our motorhome is our home when we are gone for months at a time. If the motorhome needs to stay in the shop overnight that is where we stay. Needless to say we either have no electricity or if we are lucky we are able to connect to one of their 15-amp circuits.

Then there are times when we "dry camp" or "boondock" whatever term you prefer. That is spending the night in our motorhome without any connections to water or electricity. You might not be planning to do this but let me give you a hint. You will.

You may find yourself dry camping in a Wall-Mart parking lot when traveling to a destination half way across the country. Don't say it won't happen. If you happen to have an emergency back home and are forced to travel across the country in a hurry you may find yourself stopping in a truck stop, shopping center, interstate rest area etc., to catch a few winks before heading on. You also may find yourself spending more time than you would like in a mechanics shop. Or you may want to enjoy a National Park Campground like in the Tetons or Yellowstone. For the most part National Park Campgrounds don't have utilities at each site. That is why I am stressing the importance of understanding your electricity systems. It is too late to learn when you get to these places. Well, actually it isn't too late. You can always try to learn on the fly but I can assure you that "Momma" ain't going to be happy and you know how it is when "Momma" ain't happy. Nuff said!

That pretty much covers 120-volts except to say that when you are connected to campground electricity your motorhome will automatically switch your refrigerator to work on 120-volts instead of propane. When connected to external power the refrigerator uses a heating coil in place of a propane flame. You may also have an electric element in your water heater that will automatically be on whenever you are connected to external power. I say may have because many of the newer RV's come with water heaters that are both propane and electric. Anytime you are connected to external power you need to know that these appliances are drawing power.

Now let's look at 12-volt systems:

Yes, RV's have two types of electricity that power equipment in your RV. There is high voltage as in 120-volts AC like you use in your stick & brick house. Then there is a 12-volt DC (Direct Current) system that many of your appliances use to operate.

A 12-volt system receives power from a bank of batteries called house batteries. Some travel trailers and popups only have one 12-volt battery but most RV's have at least two with some of the larger bus types having 8 or more. This 12-volt system powers many of the appliances in your RV and you best know which ones. It is your 12-volt house batteries that allow you to wash your hands and flush the toilet in your RV when you are not connected to city water, the water pump is a 12-volt pump.

You may think that you have a propane refrigerator, and you probably do, but without 12-volts to the circuit boards it will not operate; neither will your heater or your water heater (the 12-volt system supplies power to the control boards). If your batteries get low your CO2 detector will start going off and it is hard wired to your 12-volt system. The only way to get it to stop going off when this happens is to take a screw driver and remove the detector from the ceiling and disconnect one of the wires at the wire nut thus removing power from the unit until such time as you get your battery problem solved.
Many if not all of your interior lights will operate off the 12-volt system as well.

The fan on your propane heater is powered by 12-volts. When dry camping (without electrical connections) many RV'ers wake up after a cold night to find that their house batteries are completely run down. That is because a typical blower motor on the heater pulls 4-amps and on cold nights the heater can cut on and off all night. Four amps is a big draw when you are dry camping (without electrical connections). Again, there isn't a problem when you are connected to campground electricity but when your house batteries are supplying the power that 4-amps of draw will deplete the juice in your house batteries overnight.

House batteries are a subject unto themselves. For the most part they are very similar (size, shape and physical appearance) to the battery that we all use in our automobile. While they may look similar they are constructed differently on the inside. The battery most of us are familiar with starts our automobile. In order to do that the ordinary battery delivers a LOT of amps for a short period of time to the starter. Then the vehicles alternator quickly recharges the battery. Thus, those batteries are designed to deliver a burst of energy then be quickly recharged.

House batteries are designed to provide a continuous flow of electric current over a long period of time. They are designed to be deeply discharged (as in 50% discharged) before they are recharged. Although there are some 12-volt deep cycle batteries on the market most 12-volt deep cycle batteries are a hybrid like those marketed for the pleasure boating community. They can take being considerably run down before recharging and can deliver enough juice to start the engine. However, most motorhomes and other RV's prefer to use 6-volt golf cart batteries that are rather cheap and readily available. Two 6-volt golf cart batteries connected in series will provide many more amp hours of power than two 12-volt deep cycle batteries.

Batteries in your 12-volt system will also power your inverter. Almost all motorhomes come equipped with inverters. An inverter is an electrical device that converts 12-volts from your house batteries into 120-volt AC power so you can use your computer, watch TV, and power your DVD or VCR, electric razor or any number of small appliances. You can do this when you are not connected to an outside source of electricity. However, you can not run everything. Things like air conditioners, hair dryers, electric heaters, toaster ovens and other high-draw appliances draw too much power.

Inverters come in a variety of sizes. You can purchase a 100-watt to 400-watt inverter that will plug into your cigarette lighter outlet. Small inverters like this will power a laptop computer or some other small appliance like an electric razor. Inverters found in motorhomes will generally be 1,000 Watt, 1,500 Watt or 2,000 Watt. Even larger inverters may be found in the bus type luxury motorhomes. One that I know about has two 2,500 watt inverters. All of their appliances are total electric (no propane) not even the cook stove. The two 2,500 watt inverters will run his refrigerator on 120-volts AC when they are not connected to campground power. About the only thing he can't run is his air conditioner and cook stove. To operate those two big 2,500 watt inverters he has got to have a huge bank of batteries and he has to be careful not to drain those batteries. I can only imagine what kind of equipment he has to have to recharge that bank of batteries.

It takes battery power to run these big inverters so you will find that 1,000 watt inverters will generally have at least two house batteries. As the size of the inverter increases the number of house batteries will increase as well. Some of the larger motorhomes have 6 to 8 house batteries with some of the truly big outlandish motor coaches possibly having more than 8.

Another piece of electronic gear you will need to understand on your motorhome is your converter/battery charger. A converter converts 120-volts into 12-volts DC thus supplying power to your 12-volt system when you are connected to external electricity. Your battery will supply the 12-volts when you are NOT connected to external electricity. The battery charger will charge your house batteries when you are connected to external electricity or you are running your generator.

The motorhome alternator will also charge the house batteries if the motorhome engine is running. Thus if you overnight in a Wall-Mart, or rest area and head out in the morning your house batteries will be charged by the motorhomes alternator while you are driving. Of course 5th wheels and travel trailers do not have this option.

Usually the inverter/converter&battery charger come as one unit in motorhomes.

I have saved the generator for last. You can have all the electricity you want if you just run your generator. There are a number of reasons that people do not run generators 24/7 like noise, cost (gasoline and diesel can be expensive), rules (some places do not allow generators) and safety (carbon monoxide kills --- therefore very few people sleep with their generator running). Every year you can read stories about seemingly intelligent people dying of carbon monoxide poisoning while sleeping in their RV. Don't let it be you.

Many campgrounds like in National Parks allow generators to be run from 8AM to 8PM. In places like that you have to run your generator long enough to charge your house batteries during those hours then depend on your inverter to supply you with 120-volts until the next day.

In conclusion, you might be one of those individuals who don't want to know anything about electricity ------- except that you have to plug it in and turn it on. If you are one of them you are in for a rude awakening. In order for you to get along in your RV you are going to have to understand more about electricity than just plugging it in and turning it on. Hopefully, the discussion above has helped you understand why you will need to know more about electricity in your RV.

While my discussion was nothing more than an overview, more technical information is provided on other RV'ers web sites.

For a list of those web sites click here: WWW sites