Croix's Tent Trailer Build - something a little different

[croix]

First outing

Well my first trip with the trailer was an overwhelming success. Drove about 750 miles to camp and the last 30 miles were rocky, washboarded, dirt roads. The trailer suspension worked great. At one point I had to turn around on a narrow dirt road and had the trailer backed up onto a bank almost 90 degrees from the jeep and rotated to the point that I was looking at the top of the trailer through my side window - LOVE the Max Coupler. I was going to get a picture but a forrest service truck came down the road and since I was blocking the whole road I needed to get moving. Setup took about 20 minutes (including sleeping bags etc.) and tear down took about an hour (largely due to hangover status). My buddy and I spent 11 nights in the camper and despite being very small, we didn't feel overly cramped. The beds are 4 feet wide so we kept bags, clothes, guns, etc. outside our sleeping bags and still had plenty of room to sleep. Almost everybody else that was at our campsite felt that the bottle opener made the whole trailer worth the effort. Everybody that stopped by our camp asked about the little camper. "Where did you get that?" "What the h*ll is that?" "You built that?" "1952 what???"

There were a few little hangups on the trip.
1. The cold and rain caused the insulation under one of the beds to come undone - I must not have prepped the surface well enough. It was warm enough on this trip that the insulation wasn't missed but it will get replaced.
2. One of the wires to the airbag controls got knocked off when packing the storage cabinets. With a little contortionist activity on my part I was able to reconnect it, but I'll need to build some sort of shield to prevent that, and will probably build one for the compressor in the tongue box while I'm at it. Nothing happened to the compressor on this trip, but the air lines are pretty exposed to things bouncing around in there.
3. I air down the airbags at camp to lower the trailer enough for the rear door to work as a step (as designed). Because of the akward angle that we parked at, one of the tires was able to push up into the fender without hitting the bump stops when I let the air out. It wasn't enough to cause any damage to the fender, but it did allow one of the airbags to roll off of its seat. Luckily, I was able to roll it back on once we leveled the trailer. I may need to put the bump stops farther out (outside the airbags) but haven't had a chance to look at it closely. For now, I will just make sure I get the tires close to level before airing down.

Overall, I'm really happy with where it is now but can't wait to make it even better. Here is a pic at our camp:



-croix

 

[croix]

Solar - and lots of math.

I've known since I started this build that it would have solar power one day. My initial thought was to throw 120 or 135 portable kit on and call it a day. Well I just started seriously researching solar options for my little camper and HOLY CRAP! Lots of math. I've read several posts in this forum and others. I've found and used various calculators. I've looked at specs on soooo many panels, controllers, batteries, and monitors that my head is spinning. My goal is to never need electrical hookups and stay as long as I want. The basic DC loads are pretty easy to support. LED lights, heater, and water pump. That's about it really. Things get tricky when I throw in my CPAP (sleep machine for sleep apnea). This is where the math starts :Wow1:

The CPAP has a 60 watt power supply which on 120Vac is .5 amps (60/120) - almost nothing. That same 60 watts supported by 12Vdc is 5 amps (60/12). Due to losses and inefficiencies associated with inverters it becomes more like 5.52 amps. Assuming 8 hours of sleep (I don't often sleep that long while camping but I want the ability to) that is almost 45 amp-hours per day. My current group 27 battery has about 90ah rating and since only 50% of that is usable, I would essentially drain my battery in a single night. Despite the fact that my battery will be replaced with two 6 volt batteries for 400ah, I will still need to replace the 45 ah that my CPAP uses (plus the 10 or so amp-hours used by everything else). So will my 120-135 watt portable kit idea work???

Ummmm.... no! How do I know? ugh - more math. The Samlex 135w kit has a peak voltage of 17.7v and peak current of about 7.63amps. Most of my camping will be in zones 5 & 6 of the solar insolation map which experience an average of 3.5-4.5 hours of peak sun each day (I will use 4 hours for my math). Add in "weather factor" of 1.55 and the "effective" hours of sun is reduced to just 2.58 (4/1.55) hours per day - YIKES. That gives me 19.68 (7.63x2.58) amps per day from the 135watt kit. I would be losing 37 amp-hours per day. My 400ah battery bank would last a little over 5 days before I would have to recharge with some other method besides solar - not acceptable for my goals.

So how much solar do I need??? aaggghhhh - more friggin math. Without getting into 24v or 48v systems, 12v panels typically have a peak voltage between 17.7 and 18.38v. I'll use 18v for my math. To compensate for the roughly 55ah usage I would need (55/2.58)x18 or roughly 385 Watts. I realize that there are some other innacurracies in my math and I've assumed the absolute worst case for much of this, but still feel I'm in the ballpark.

Sooooo... with a couple of 150w panels I've figured out that I can make it about 15 days without a need to recharge 400ah batteries by some other means (a/c charger or vehicle). I don't normally camp for more than two weeks so I think that may be where I end up. Now I just need to figure out how I can mount/use such panels.

I don't mean for this to derail into a full blown solar discussion and I know that there are specific boards for this. I just wanted to give you all an idea of what I've been up to and where I'm going. After Christmas I'll be saving my pennies for a solar setup. In the mean time I'll be racking my little brain to figure out how I'm going to make this all fit on a 4'x6.5' camper. I'm sure that will involve more math

-croix

 

[drgrenthum]

I feel your plight with the solar. I too want to be completely off grid with it on my trailer.

I went with the Midnight Solar classic charge contoller, 24v worth of batteries and I am getting 750 watts of panels. As you alluded to in your post as the watts go up trying to stay 12v just is not practical especailly considering the price per watt on 12v panels. I highly recommend larger panels pushing 30+ volts and using the charge controller to regulate to whatever final volatage you decide. It will greatly increase the amps you are pushing out. You can always get a 24v to 12v inverter, of course you have to add in additional losses but i think the pluses out weigh the minuses. There are of course 24 to 120 inverters at roughly the same cost as 12 to 120.

I am doing the panels in a trifold configuration on a tilt stand that will only be deployable when parked. Panels being roughly 65x40x2, they are larger but surely you can figure out a place you can put them and then fold them out.

 

[croix]

drgrenthum - first of all, curse you for making me re-do all of the math Second - the math was worth it. 24v adds a little complexity and the panels are more expensive, but in the end I think I can get it all done with a single panel instead of multiple panels. The CPAP is the biggest load and going to 24v cuts the amp-hours in half so that alone makes this a no-brainer. I'll have to add a 24 to 12 converter for the dc loads but I can go back to 12v batteries in series (instead of 6v) so the overall cost is pretty close to the same. I haven't had time to research the exact components I want yet but 24v definitely seems like the way to go. Thanks.

I will be interested to see your trifold design. Be sure and post that build.

-croix

 

[croix]

It's been a while since I've done anything on the trailer. Spent the summer backpacking in the Olympic mountains without any need for the little camper, but with an upcoming trip I decided to add a couple things.

First add was propane tanks.


I went with the Worthington 2.6 gallon tanks which were about 1/4" too tall so I cut holes in the side-steps and set the tanks into the holes.


The holes helped secure the bottom and I can put a padlock on to deter thieves. Then I used Quickfist straps to secure the tanks to the body.


Right now the only thing that needs propane is a little buddy heater that I will just connect with a long hose and use once in a while to dry things out in the tent. Eventually I will support a propane cook stove in the same way. Next up... water.

 

[croix]

I bought 2 10 gallon tanks from Plastic-Mart. I actually designed the frame around these tanks which I wanted because they were only 4.75" deep and didn't hang down too far. My initial plan for mounting didn't work so well and I had to make some adjustments but overall it worked out pretty well. One tank is just forward of the axle and the other is just behind the axle. This should minimize impact on tongue weight.

This is looking from forward to aft.


I mounted the water pump just aft of the rear tank.


The pump outputs to a quick disconnect on the rear passenger side of the trailer.


I have 2 lockable fill ports on the driver's side of the trailer; one forward of the fender and one aft.



The switch for the pump went just inside the door under the passenger side bed.

 

[croix]

I bought the Quickfist straps as part of a kit which came with 2 large, 4 medium, and 2 small straps. I decided to put the extra straps to use.

The medium straps now hold a shovel and axe inside the tailgate of my Jeep.

The small straps were used to mount a Phillips screwdriver and 1/4" nut driver inside the tongue box. These tools are used to set up the tent on the trailer and it's nice to have them readily available.

Now I think I'm ready for the next trip which will be 14 days in the northern Selkirk mountains of Washington. Should be a good time.