Mechanical & Electrical Systems - Utility Cargo Trailer Camper Conversion

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Mechanical & Electrical Systems


Rather than going into verbose detail on the mechanical and electrical systems, I will discuss them briefly and you can review the "Photo Gallery" along with the water and electrical diagrams below. Several keys to consider were:

  • Water cannot be allowed to back-feed either way from the city water into the on-board fresh tank nor from the internal tank and pump into the city water (which would also discharge your fresh water out the connector on the outside). Therefore there are several backcheck valves to make sure this does not happen.

  • Water pressure could be high coming in from a city connection. We included a pressure regulator with the incoming connection and also use an external one just to make sure we don’t risk blowing apart the internal plumbing when a campground doesn’t properly regulate their water pressure.

  • In a similar way, 120v electric cannot be allowed to come concurrently from an external AC connection and the internal inverter that converts power from the on-board battery into 120v AC power.  

  • Rather than purchase an automatic camper power converter box, I used a manual 3-position switch. The middle position leaves the 120v AC sockets off. One way connects external AC to the breaker panel and the other way connects the inverter 120v output to the electric box. If I were to do this over, I would run a separate circuit to the outside 120v outlet. This would allow it to be turned off separately so someone else can't  pug something into the external outlet while I am operating on 120v from the battery/inverter and run down my battery. (Although this has never happened, I have attended a music festival where AC power is limited and people will plug in a cord wherever they see an AC socket.  SoI may still make this change.)

  • Fridges are availabe for campers that run on LP or electric. However I opted to just use a cube fridge (about 1/6 the cost) that only operates on 120v AC. This means that when disconnected from external AC power the inverter must feed the 120v for the fridge. This has worked out OK to operate the fridge on the battery and inverter overnight.

  • For backup and long drives, I replaced the flat-4 vehicle plug with a standard 7-connector type that provides 12v DC from the vehicle (See the Electrical Block Diagram below). This can charge the battery so we don’t run down the camper battery during a long night drive or when there isn’t solar power to charge the battery or operate the inverter and fridge. Also note the diode in the electrical diagram. This prevents power from flowing from the battery back to the vehicle. There may be a similar protective circuit on the vehicle. However, I didn't want to assume this when this extra layer of protection won't cause any problems.

  • We count on the 12v battery, charged by solar, for lighting, water pump, and inverter. I did not think we needed the 120v to 12v converter that I included on the electrical diagram below. After about 50 days and nights in the trailer, we have verified that a 120v-to-12v inverter is not needed.

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