If you are building a Camper there are actually 3 Electrical systems to consider. The first electrical system to consider is the truck or trailer system. It doesn’t matter if you are building a truck camper, a teardrop trailer or doing a horse trailer conversion, the first electrical system to consider is the one that connects to the truck hauling the camper or the tow vehicle that connects to the trailer.
This electrical system controls all of the signal lights, brake lights, and marker lights of the truck or tow vehicle. There is also a lead in the plug that can charge the batteries of the Camper. This plug is generally a 7 pin plug and contains the following wires. Brake lights, Left Turn Signal, Right Turn Signal, Marker Lights, Brake Controls, Ground and 12 volt to charge Camper Batteries.
When wiring your Camper for these lights you will want to run both a power lead and a ground lead to all lights. This will save you hours of troubleshooting trying to find a missing or loose ground. It is also a good idea to run all of the wiring for this Electrical system before you put on the outside sheathing.
The second Electrical system that you should install in your camper is the 12 volt system. This system runs off of your Camper Battery system. In your Camper you will want to put your batteries in a lockable access hatch that is accessible from the outside of the Camper. You can use lead acid batteries, agm batteries or Lithium batteries. The biggest consideration is that the batteries be Deep Cycle.
The Battery compartment should be sealed from the inside of the Camper and should be heated especially if you are using Lithium batteries. Lithium batteries won’t recharge if they are below freezing.
This Electrical system will power your interior lights, porch lights, your furnace, your fridge, water heater, water pump, range hood, and any other devices that run on 12 volts in your Camper. All of the devices that are powered by 12 volts should be run with a 12 volt line and a ground. All of these 12 volt leads should be run back to a fuse panel. The negative lines should all be run back to a bus bar. In most cases the wiring can be #14 and fused with 15 amp fuses or breakers. The fuse panel will be fed from the Camper Batteries.
The Batteries in the 12 volt Electrical system can be charged several different ways. The basic way is to charge the Camper Batteries using the tow vehicle or truck electrical system. When the Camper is connected to the vehicle and it is running, the Camper batteries will charge.
The Batteries can also be charged using Solar Panels. If you are using Solar Panels you will also add a Solar Controller. The Solar Controller will allow you to charge your Camper Batteries without over charging them.
The other way to charge you Camper Batteries is by way of a shore plug and a battery conditioner charger. When you are connected to shore power you can run a batter conditioner that will keep your batteries charged while you are at a camp ground or parked at home.
The next Electrical system that you want to consider for your Camper is the AC 120 volt system. This system will power any 120 volt outlets you install in your Camper. This electrical system will be powered by your Camper batteries by using an Inverter. It will also be powered when your Camper is connected to shore power. A good idea is to mount all of your outlets for the AC system in device boxes. You will also want to connect your AC system to a Breaker panel.