Electrical upgrade, stage 1, I've reached a milestone in my project to upgrade ...

I've reached a milestone in my project to upgrade the electrical system in my '90 Casita, so I thought I'd give the forum an update. I've tinkered with alternative energy in my home for a while, but my systems were always too small to make a dent in household electrical usage. But in the Casita I could use the same equipment and have a very robust self-contained system that could make a big difference, and I would be able to utilize gear I already had.

The goal is to install an inverter, golf-cart batteries, and a solar panel on the roof. The picture here shows the sophisticated test setup with the Trace UX1112SB inverter and two T-105 210AH batteries. The batteries are available from Sam's Club, or most battery distributors. Left of the batteries is a ceramic heater for AC load testing, to the right a resistor bank for DC load testing.

Attached Image

The trickiest part turned out to be physically mounting the Trace. It wouldn't fit in the power converter space in any orientation except on edge, so I was unable to just bolt it to the floor. I built up these two rails, top and bottom, out of 2x2 stock, with a 2x4 under the bottom rail to lift it up. There are also some thin spacers between the top rail and the fiberglass seat to fill the gap. Fastening is all with wood screws. The entire bulkhead had to be removed to make a gap big enough to fit the Trace through.

Attached Image

Here's a close-up of the bottom rail. The edges of the 2x2s are reinforced with mild steel L-brackets. I used steel because the Trace is very heavy and I didn't want something that would work loose or fatigue as the trailer bounced. The brackets are drilled and tapped 1/4-20 for the Trace mounting holes because I would be unable to reach behind them to use a nut. You can see here that I extended the lower bracket out beyond its wooden base in order to leave space for the tubing and wires passing through the area.

Attached Image

Here's the Trace bolted to the rails. The UX1112SB has a 1100 watt continuous capacity, but it can supply three times that for nearly a minute. It also includes a 30-amp automatic AC transfer relay and a 50-amp 3-stage battery charger. I bought mine from Mr. Solar, they have them for around $670.

Attached Image

Here's a view of the Trace through the electrical port. The factory 14-guage 15-amp extention cord was replaced with a 10-guage 30-amp pigtail plug -- no more room for extention cords in this space!

Attached Image

Here's a picture of the 200-amp T-type fuse and holder mounted on the floor behind the water heater. The wiring is 1-guage marine-rated attached with aluminum compression lugs. Positive lead is wrapped with red tape, at the bargain price I paid I could only get black. The trailer's DC system taps power from the fuse block (green wire).

Attached Image

Picture is of the 500A-50mv shunt used for the Link 10 battery meter. A shunt is basically a very small value calibrated resistor that produces a voltage proportional to the current flowing through it. The Link 10 measures this voltage and calculates the current flowing through the negative lead to or from the battery. More on the Link 10 later.

Attached Image

You may be wondering what happened to the previous occupant of the space the Trace now occupies. The Carson power converter was disassembled and parts of it will live on in the new system. Here is a shot of the front panel of the Carson which I built into the power distribution panel. Upper-left are D-Square breakers for the two AC circuits, upper-left are the DC fuses. Lower-left is the button to turn the Trace inverter on/off, and it also blinks to show inverter status. Lower-right is a DC appliance socket using Anderson Power Pole connectors which I prefer over the cigarette lighter kind. Paint job is baked-on enamel -- literally: I stuck it in my oven.

Attached Image

Shot of rear of distribution panel, all wired and ready to mount. All AC wiring is enclosed, as required by code.

(Of course I meant upper-right for the fuses in the previous post.)

Attached Image

Eric:

Great, what wattage solar panels do you have in mind?

One statistic that comes to mind is that a 45 watt solar panel will work a week to produce the same power a Honda eu2000i generator makes in an hour.

The T-110 batteries are rated at 210 amp hrs at 6v. So two in series is still 210/12vdc, right? Would you expect 13hrs or so of operation from the ceramic heater before depleteing the batteries?

Have you run your ceramic heater on an endurance (time) test?

What 110vac uses do you have in mind for your inverter?

Where's your batteries gonna go?

What size/floor plan Casita?

Solar is my next project.......Don in OKC

Detail shot of inside load center box. Any electricians out there want to check my wiring for me?

Attached Image

Shot of power panel and Link 10 installed in final position. Note that bulkhead doesn't run all the way to the ceiling any more. More on that later.

Attached Image

Close-up of Link 10 battery monitor. This handy device is like a gass guage for your battery. It reads out voltage and current, but it also keeps track of amp-hours used and percentage of battery capacity remaining. It can compensate for temperature and for the decrease in battery capacity as the current increases. There are also options for sounding an alarm or automatically starting your generator if the voltage gets too low.

Note the first "Oops!" hole I made above the Link 10, where it didn't have enough clearance to fit. I can't tell you what I said when I found I'd done that, it's rated R. I put the plug back in with some epoxy, but it needs a bit more cleanup. Oh, well, nobody's perfect.

Attached Image

As I said before, the floor-to-ceiling bulkhead went away. I couldn't figure out why it was needed, and it was turning into a pain to get back in place. I took the lead from someone else here who trimmed theirs down and went one step further and cut the middle out entirely. I think it will make the trailer's interior space seem more open, and it also eliminated what I thought was a tacky feature where people in the dinette had to look at the backside of the particle board. Here's a pic of the end piece for the overhead cabinet, I used the original part as a guide and cut a mirror-image of it so that the vinyl finish is showing. I installed the knob so I could hang things from it.

Attached Image

That's the end of stage 1. Stage 2 involves relocating the water pump to the opposite side of the trailer to make room for the batteries, and building and installing the battery tray. But that, as they say, is another story.

Don: Solar panel will be a Siemens SR-100 100W. I'm working out the details of mounting it, my current best idea is to use rubber radiator hose as a flexible mount. Should be enough capacity to be pretty comfortable if you keep your expectations low.

You're correct on battery capacity. You could probably run the ceramic heater an hour on those batteries, it draws about 100 amps -- not a very good use of the system.

The inverter is probably over-kill, I don't have many uses for AC at this point, but it integrates a lot of components I would have otherwise had to install separately, and the AC distribution in the Casita is much better than the one for DC. It also means I don't have to pay extra for AC/DC appliances.

The inverter is about 90% efficient. Considering you loose almost that much in wiring resistance when you run the fridge on DC, that ain't bad.

My Casita is a 16' Freedom. I think I can get the batteries into the space aft of the water heater if I take out the pump and re-route the plumbing a bit. I'll have to wall off the back half of the space as a battery box.

The owners manual on my Scamp said that the interior panels helped to support the roof of the trailer. It specifically said that if one was removed for repairs for any length of time the roof should be supported, particularly in the instance of the closet, which is just to the left of the door as you enter a Scamp. It seems that the door area would be one of the weakest sections of the camper due to the large opening there. Also, on the Scamp there were metal supports between the lower and upper cabinets next to the dinette. It appeared that these helped transfer the weight of the roof and the upper cabinents and their contents to the lower cabinets and on to floor of the trailer. I would be a bit leery of completely removing a bulkhead as this could allow the roof to vibrate which could cause it to crack. Just my opinion. :-)

Could be, but the bulkhead only extended in a few inches from the wall, and that curved section is the strongest part of the roof. From how loose the L-brackets that connected it to the roof were, I can't believe it was bearing much load. The middle of the roof is where the forces are greatest, I think that's why Casita puts that ridge down the middle.

The Liberty model doesn't have that floor to ceiling piece of wood at all. So it can't do to much in the way of support.

Carol

Jeese Eric! Here my biggest concern is making a good marguarita while dry camping, and you go and tear up your entire trailer to go solar, with inverters and big battery packs!

Can I bring my electric blender over to your trailer at next year's rally?

Really sounds like a neat system. You and Morgan ought to go into business together ... you both sound like electrical geniuses!