AC-DC

2016-10-10

For $24,000 you don't get an inverter to convert the DC battery power to 120V AC power, so I hatched a plan to put one in.

I originally wanted to put the inverter in the front of the trailer so I could hook it up to one of the AC outlets near the dinette. For various reasons that idea just wasn't winning any awards. Someone at work casually mentioned that with the inverter I could run an extension cord out to the telescope from the trailer. The light bulb went off. What a concept! I had only thought about using the inverter power to recharge batteries for the telescope equipment during the day.

The best place to put the inverter became the starboard wheel well compartment.

First step was to get DC power over to that side of the trailer. There was a bunch of it in the port wheel well, but only small wire stuff for the outdoor light on the other side. I decided to run some 10ga. wire around under the couch.

Above was the connection point for the negative side. Who the hell with a degree from kindergarten wires something up like that?? When I removed the wire nut many pieces of wire fell out and within seconds one of the whole wires fell out of the bundle. There was a similar mess hiding under the red wire nut for the positive side. This caused a project detour.



I ordered two Blue Sea System bus bars, put crimp-on rings on the end of everything, and at least cleaned up the two large positive and negative bundles of mess. There's still a lot of wires down there, but all of the remaining wire nuts are only connecting two or three wires together and I can live with that. You'll notice in this picture that NOTHING is marked, and there doesn't seem to be any schematic for the wiring. Another present from Aliner, Inc. I'll get that taken care of someday.

The inverter was a regular Cobra 800W variety with two AC outlets and a power switch on the front. The DC connections were bolts with nuts/knobs on the back. I mounted the inverter to a piece of plywood then simply Velcro'd that to the wheel well tin. That allows the air to circulate under the inverter and makes it easy to replace after I burn it up. Also, that single sheet of tin is all that's between the inside of the compartment and a tire coming apart while going down the highway, so I didn't want to be drilling through it or anything. I came up with the idea to use short electrical cords with regular three-prong plugs to connect to the outlets on the inverter. I snipped the other end connectors off to get the bare wires. There was one double outlet in that area of the trailer, and one on the outside of the trailer. The back of both of them were in the wheel well area where I was putting the inverter. How convenient!

Done. The red/black wires are the 10ga. DC ones coming from the other side. The black wires running to the two outlet boxes are the ones with the plugs on their ends and they are plugged into the outlets on the front of the inverter. One cord is wired to the inside dual outlet, so both AC outlets are powered from the inverter. The other cord is wired to only one of the two AC outlets of the dual outlet on the outside of the trailer. The other outlet of the pair gets its power from the normal AC system that gets power when the trailer is plugged into shore power. Clever. The power switch for the inverter is just to the right of the cord plug that you can see which is to the right of the yellow wire nuts. It's easily accessed by reaching into the well. The single white outlet was for the microwave and still gets energized when the trailer is connected to shore power.

To make it easy to get at the power switch I had to alter the hatch covering the compartment. To get those hatches off you had to lift up the seat cushion part of the couch just a little. I chopped off 1 or 2" of the end that was under the couch and made that piece permanent. Drilled a 1-1/2" finger hole in the other section and no more having to lift the couch.

Opening the hatch, reaching in and flipping the inverter power switch on and off lasted exactly one camping trip. It was one of those First World annoyances. I ordered a lighted on/off switch from Powerwerx.com and wired it into the red DC wire going to the inverter. The power switch on the inverter is left in the ON position, and the inverter is controlled using this lighted switch. Much better.

2018-03-03