Planning to convert a 6x12 cargo trailer.

[rebelrider.mike]

A couple years ago, I wanted to build a tiny teardrop for my motorcycle.
http://www.tnttt.com/viewtopic.php?f=50&t=68000

Unfortunately, I've developed some health issues, and won't be able to do that after all. Still want to go camping though, so now I'm planning a cargo conversion for my little truck to pull. Advantages will be enough space for my wife, and the convenience of an enclosed vehicle while driving. Also, a bigger alternator.

Anyway, I hope to buy the trailer next year sometime, and until then, I'll be gathering info here and across the internet, and making some designs. Hopefully this project will actually happen, LOL. Until then, I'll share stuff here, and hopefully you all can give suggestion as I go.

[Modstock]

Welcome to the cargo trailer section. In the meantime while start looking at cargo's in your area and different manufacturers.
When I picked mine I did notice one brand was tougher than another I wanted but....In the end it all came out to height. I wanted it to fit in my shop's 8ft door.

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[rebelrider.mike]

I've looked around at trailers for a couple years, and I've settled on a 6x12 with "barn doors" in the back. Empty, it's less than half the weight of my truck's towing capacity, and I'm confident I can keep the post build weight low too. Also comes with LED exterior lights. I'm planning on buying it this winter some time, hopefully when prices are lower.

My goal with this is to keep it simple and have something I can just park and sleep in. Without having to do a lot of setup first. But I've got a few ideas to make it nice too. I figure it will be a semi off-grid trailer, but I don't have the money to run 120v things off an inverter, so some conveniences will need external power.

So for power, I'm thinking 12V solar, power from the truck while driving, and power from the grid If we're next to a hookup. Amps from solar will depend on how many panels I can fit on the roof. I'm thinking 5A from the truck, and whatever the maximum current is for the battery from the grid. I'll have to figure out details later. Also, a small generator for AC stuff.

The battery will be a 24V Lithium iron phosphate battery. Don't know how big yet. DC stuff will include LED lights, a 12V socket for whatever, a 24V socket for my CPAP. 5V USB sockets for charging phones and things, fans, a 12V cooler... I think that's everything for now. For AC stuff, I think a small microwave, 500-700 Watts, and an air conditioner. I read somewhere that the power rating for microwaves is for the output, and that the input is up to twice as much. But if we're on grid power, it won't matter too much.

Plumbing will be easy. I plan to put a water jug on a shelf and gravity feed it to a faucet. The sink will probably be a salad bowl with a hole in the bottom. That'll empty into a bucket, or maybe just a drain through the floor. No toilet, no shower. Hot water will be heated via propane outside on a stove. I'd like a counter top by the sink for food prep, but we'll do the cooking outdoors.

A few ideas I've read here lately are a cellular signal booster, and interlocking foam mats for the floor.

[hankaye]

rebelrider.mike, Howdy;

Welcome to the maddness

From what you state your goals are this thread and the builder are
who you might want to strike up a conversation with.
viewtopic.php?f=42&t=73788

hank

[onehoser]

welcome! i’m also building a basic, light weight 6x12.


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[rebelrider.mike]

Thanks all!

I've been thinking about coolers. From what I've found so far it seems that there are 120VAC mini fridges, and 12VDC thermoelectric coolers.
I'm not sure which would be better for my application.

A thermoelectric cooler would be simple enough that I could build my own for a fraction of the cost of buying one. Also, the commercial units are tiny. 1.6 CFt. They have no thermostat, so they draw about 5A as long as they're plugged in. I could build a larger one with two peltier chips, a few fans, and a thermostat. It would use about 12A, but would only run while warm inside. So it would draw 144W from the battery. An issue with thermoelectric cooling is that it's only around 30% efficient. At least that's what I've read. So the cooler would generate twice the heat outside as it dos cold on the inside. I've been playing with pelier chips, and they do indeed get cold enough to freeze condensation right out of the air, but they generate a lot of heat.

A mini fridge That runs on 120VAC might be a better setup. It looks like a very basic 4.4 CFt without a freezer uses around 1A, or 120W. I'm thinking a 500W pure sine inverter would be sufficient to run the fridge off the battery. And I could switch it to grid power whenever we're plugged in. I haven't been able to find a number as far as refrigerator efficiency, but I'm pretty sure that they are much more efficient that thermoelectrics.

So given that mini fridges and smaller pure sine inverters are readily available and not outrageously expensive, I'm leaning towards that. Maybe some of you all have figured this stuff out already? I'll continue to read and search on this.

[flboy]

Careful with the mini fridge and assuming because you can run it on a 120W that a 500W pure sinewave will run it. It may indeed run it, but you won't know until you try it. I use the 110VAC minifridges and like them and think they work well; however, some of them can draw up to 10x normal current on startup just for a few miliseconds and that will trip a 500W inverter which should have 2x or 1000w momentarily.

Then again, not all will do 10x..some are less. Just check it. They may specify LRA (locked rotor amps) and you want to size your inverter for that with some margin.

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[rebelrider.mike]

Good idea. I think I'll get the fridge I want, then try out inverters. Easier to send back the inverters if they don't work.

[Gulfcoast]

I recommend a 12 volt compressor refrigerator... mine works perfect.

[featherliteCT1]

My 500 watt Renogy pure sine inverter runs my 3 cu ft 120v freezer just fine. It is worth a try.

[rebelrider.mike]

I was thinking about how much power I would need from an electrical hook up at a campsite, and I realized I have no idea what they provide. I've only ever been a tent camper. I looked around briefly on the net, and found that campsites might offer 120VAC 20A, 120VAC 30A, or 240AC 50A.

Are those pretty standard? Should I build a system that could use any of them?
I'll keep searching and reading, but advice is certainly welcome.

I've been adding up all the stuff I'd like in the trailer and made a schematic of how I might do the wiring. It's not conventional, so it might be hard to read, but it gives me an idea about how much power I'll actually need. It's a work in progress, as I don't have all the information yet, but here it is so far:

CargoCamperElectrical.jpg (77.19 KiB) Viewed 3712 times

I guess I should ground the trailer body to the grid hook up too. I wonder if that will be an issue with the running lights, since they're grounded through the trailer back to the truck's battery. I need to do more reading...

[hankaye]

rebelrider.mike, Howdy;

I know NOTHING about doing work on electricity!

Ok, got that outta the way, I dwell in an RV, have for over 10 years, that said I don't give
any kind of electrical advise other then listen to those that do. There are a few on here
but, and it's one of those buts that is optional. I get a weekly news letter about RVing and
they have an electrical expert that gives advise weekly. Below is a link and funnily enough
an article from yesterday about your question. There are also some links about his qualifications
and a book he's put out there for folks like us.
I HAVE NO DOG IN THIS FIGHT just trying to forward a knowledge source.
https://www.rvtravel.com/rv-electricity-rvt-1010/

hank

PS. Here's a link to 53 pages of his knowledge that he's generated over the past few years;
https://www.rvtravel.com/category/rv-el ... ewsletter/

[flboy]

Any particular reason for the 24VDC battery bank? Seems you are adding a level of complexity with the Buck converters and etc. not needed. A 24VDC battery Bank may be advantageous if you were running a huge inverter and were trying to minimize line loss from Battery to Inverter. You can minimize that if you just put the inverter as close to the bank as possible. In any case, you can run a 24VDC Solar array into the 12VDC battery Bank. The Solar Charger will handle to conversion and charging.

On the campgrounds, just carry a 50A to 30A adapter and a 30A to 20A adapter an you will have your bases covered. Most will have all three, but I have run into situations where there were no 20A and I use 20A.

Good luck with your build.

[rebelrider.mike]

Thanks for the links Hankaye! Lots of information there. I haven't read it all yet, but now I'm definitely grounding the trailer body.

I'm using a higher voltage battery for a couple reasons. The main one is so that the battery will always have a higher voltage than all the 12V stuff. So the buck converters will always be able to keep the LED lights and fans at a constant 12V, which would keep them running at the same brightness or speed all the time. The other reason is that I might be using a solar charge controller that boosts the voltage instead of bucking it like most controllers do. An odd little machine, but it's programmable, and has a nice little screen that provides tons of info, and can work with many battery chemistries. Anyway, I want to try it out a bit before deciding if I'll actually use it.

My CPAP can work between 9V-30V, so it won't need a converter, and the USB ports would need one anyway. Though now you've got me thinking, I realize that the inverter won't run on 24V. It's designed for 12V. I'll either have to find an inverter with the right voltage range, or get a buck converter for it too. That's going to either be a lot more expensive, or I'm going to lose more efficiency by converting things twice. Well bugger. More details to figure out, LOL.

[flboy]

If you use a Lithium Battery Bank, the discharge curve is very flat so you should not see any discernable fluctuations in LED brightness or fan speeds. I've never noticed anything like that.

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