« Back to RV News

RV Electrical Systems Explained

December 6, 2019

Basically RVs use 2 types of electrical systems. 110v’s AC like in your house. And 12v DC like in your car. The 110v outlets in your RV will supply power to your household appliances and TVs etc. This system only works when you plug the trailers or motorhome shore cord into an outlet at the campground or at your house. These cords can be 30 amp or 50 amps depending on the amperage draw of your RV. 30 amp is the average RV. This allows the use of the roof air conditioning, microwave oven, electrical outlets, refrigerator, etc. You must be aware of how many amps each appliance is drawing. An air conditioner draws about 16 amps. A microwave draws about 13 amps. Converter draws 4 to 6. Add up each item that you have running at the same time including TV’s, coffee makers. To see what your amperage draw would be. Larger trailers and motorhomes use 50 amp systems so they can use more/ larger appliances. Like washers and dryers, ice makers, second air conditioners, electric water heaters. Something else to consider is just because you have a 30 or 50 amp plug at your campsite. Does not mean that you are receiving that much amperage. Campgrounds may only have so much power to use. If the campground and all the other campers are using a lot of power. You will not have the amperage you expect. The best way to monitor this is with a 110v volt meter. When volts get low this means you don’t have enough amperage coming in. What should you do. Start shutting down things that are plugged in like air conditioners, coffee makers. All of them effect the 110v ac operation. Another item effecting your 110v service is extension cords. If you need an extension cord. Make sure that it is the correct cord. 30-amp system should use 30-amp extension cord. 50-amp system uses a 50-amp cord. They can be expensive but it is better than burning up any appliance or your RV. Plug in voltmeters are available at your parts and accessories store. Also available to protect your RV electrical system is called a system surge protector and ground fault interrupters. These can be installed two ways. One way is plug your power cord into it and plug the surge protector into your sites power source. These can be 30 or 50 amps. The other type can be hard wired into your system. So you don’t have an extra piece to plug in. What these do is if there is a lightning strike or a power surge in the campground. The surge protector will pop. So your RV will not be damaged. The other protection that these give is if you get a short in your RV or at your site the occupants won’t be electrocuted. The device will pop until the problem is fixed. When they pop they can be reset.

The 12v electrical system in your RV operates from power supplied by a battery or batteries. The power goes from battery to fuses to lights, furnace, refrigerator, water heater,… The biggest thing to remember about the 12v system is that the battery only has so much power in it, and it can run out of power. The best way to keep your batteries from going dead is to use your converter to keep the batteries charged. To operate the converter you must have 110v ac from your shore cord at the site. What a converter does is converts 110v ac to 12v dc. Most converters also charge the batteries at the same time. Converter size is very important. If you have a large RV with a lot of lights and 12v appliances. You should have a larger converter. Generally converters run between 30 amp and 75 amp output.

If you do a lot of dry camping – which is camping without hookups, no power, no water. Than you need to understand your system even more. If you use your battery power all up the first night. You will need to recharge your batteries. Other energy saving habits include. Shutting off lights when not in use. Installing additional batteries. And recharging the ones you have. The recharging can be done by either starting the engine of your motor home, starting your generator, or plug your tow vehicle into your trailer (if your tow vehicle is equipped with a charge line). Keep the engines running for a few hours. Other ways to recharge your batteries are solar panels. Solar panels on the roof of RV they recharge at a slow rate. but as long as the sun is out and you are not using anything. The solar panels also work well at keeping the batteries up while the RV is not in use.

The other question people have is how can I use my microwave or other 110v appliance when I am dry camping? There are two accessories that can do this for you. First being a generator. This is usually for fifth wheels and motorhomes. All you have to do is start the generator from inside your RV. Wait for the automatic change over switch to switch to generator power. In about 1 minute you will have 110v power. To power all your ac outlets, generators, converter, and microwave. Draw backs to using the generator are: some vibration, some noise, and some exhaust. It is still better to have the extra electricity. What size generator do you need? What appliances do you want to operate? A permanent mount generator can put out 4,000 to 10,000 watts. The average needs are between 4,000 and 5,000 watts. You do have extra maintenance to do because you have an extra engine. The second appliance that is available to provide 110v power is an inverter. An inverter takes 12 dc power and inverts it into 110v dc. This will only work as long as you have enough battery power. When using an inverter you don’t have any noise or exhaust. What size inverter do you need? Once again add up the amps that are drawn from the items you wish to use and how long you want to use them for. The next thing to find out is if your batteries are holding that much power. There are formulas to figure this out. However the easiest rule of thumb is 1 battery per person plus 1 extra. What type and size battery do you need? For household usage. A deep cycle battery should be used. For chassis use a chassis battery should be used. Match the battery to the usage. Deep cycle batteries look very similar to automotive batteries. The biggest difference is that the plates in the cells go deeper to last longer at providing daily usage power, and can recharged back to 100%. When drained to empty automotive batteries don’t come back completely. Care for either is about the same. Check water in the cells, clean terminals and the top of the battery. Look for amp hour ratings on the battery. This is how power capacity is measured.