How does the electrical system work?

The electrical system in your RV can seem complex and confusing until you have a basic understanding of how it works. What you as an owner really need is a basic understanding of your RV electrical systems so you can be prepared not only to use your RV anywhere you need to, but to protect your appliances from expensive electrical damage.

Your RV electrical systems can be broken down into two categories:

  • 12 volt systems. Your 12 volt systems are run by your RV batteries.
  • 110/120 volt systems.  Your 110/120 volt systems are run by plugging your RV in or turning on your generator.

12 Volt DC System

In today’s RVs everything relies on 12-volt batteries to function–everything from the roof air conditioner to the refrigerator. Once the roof air conditioner or the refrigerator are turned on they run on 110/120 volt, but it’s the 12-volt that powers the computer that starts them up.

In addition, your water heater and your furnace are also all 12-volt computer operated.

The biggest key to keeping your 12 volt DC system working is keeping your batteries charged. There are four effective methods used to keep your batteries charged and in working order: hookups, your engine, your generator and solar power.

110/120 Volt AC system

Your 110/120 volt electrical systems run many of your daily electrical functions, including most all of your appliances.

site-hookupThe majority of campgrounds you go to will provide you with an external 120 volt electric source to plug into. Your RV has a heavy-duty power cord that is normally about 25 feet long. Depending on the type of RV you have, or purchase, it will either be a 30 Amp or 50 Amp system. When you plug into the proper campground electrical source it will supply power throughout your RV. You must have a 120 Volt AC power source if you are going to use the microwave, roof air conditioner, the refrigerator in the electric mode and the 120 Volt electrical outlets. For the most part everything else in the camper works off of 12-volt DC power. When you are plugged in at the campground a portion of the 120 volt AC current is converted to 12-volt DC current for the items in the RV that work off of 12 volts. Some of these items are the overhead lights, the furnace fan, and the fan over the range, the vent fan in the bathroom, the water pump, LP gas leak detector, stereo, and the refrigerator when it’s in the LP gas mode. If you look at the RV’s power distribution panel you will see circuit breakers like you have in your house for the 120-volt AC side, and automotive style blade fuses for the 12-volt DC side.

If you are not plugged into an external power source you can still use the 12-volt DC system if you have a 12-volt deep cycle marine battery on your unit. As long as the battery or batteries are charged you can use everything in the RV except the microwave, roof air conditioner, the refrigerator in the electric mode and the electrical outlets. Your motorhome will have a battery for the automotive system and an auxiliary battery for the coach system. The coach battery is charged whenever the motorhome is running; the generator is running, or when it’s plugged into an external electrical source.

RV Electrical Maintenance and Troubleshooting

Regular maintenance and inspection is the easiest way to spot a small problem before it becomes a big issue. On a frequent basis take a look at your batteries and all of their connections. A good time might be just before you depart on a trip. Check to make sure that all of the connection points are secure, nothing looks damaged or frayed, and everything is clean with no signs of corrosion. If you see something that looks off, it’s a good idea to have it checked out.

Additionally, know where the RV electrical panels are in your motorhome. If something’s not powering up as it should, first look to see if a circuit is tripped or if a fuse is blown. You can usually see if a fuse is blown, but sometimes you can’t. In that case, you can use a small test light that will illuminate if a fuse is good. If you replace a fuse and it blows right away, that’s a good sign that there’s a bigger problem. You can also try to follow power lines to determine if there’s a connection issue, though these can often be hard to find without professional help.

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