M116A3 Build

[lfhoward]

I like your design. The 6' width really gives you some options for storage and layout.

I'd recommending testing the 3/4" plywood for a bed platform. Even at 5' length, I think you will get too much sag/deflection.

For few ideas, take a look at Dale's Squidget with the tri-fold bench, that pulls out to make a gaucho bed.
http://www.thesquidget.com/gallery.html

Here's another way that gaucho sofa/beds were made:
http://vintageairstream.com/sofa-beds-gauchos/

Thanks! Those gaucho beds are neat. I think it would not be hard to add something like that to the design, and ultimately I'd like something like that. The low bench heigh allows for some cushions and the mechanics of slide-outs, without making the resulting seating too high off the floor. For now, I was envisioning just using 6' hardwood or hard pine boards to stretch across the trailer from side to side to support the bed. they could be removed and stacked out of the way when not in use. Something simple to get me camping sooner.

[lfhoward]

My Fan-Tastic vent fan has arrived!

[lfhoward]

Well, not much physical progress on the trailer to report this week, due to an injured elbow. I did something to it while moving back in January, and it has never healed. Now I'm in physical therapy and it is really helping-- a couple of near-pain-free days this week-- but my doctor says to give the elbow a break from heavy lifting and power tools for a while. That means I need to postpone getting wood for several weeks, unfortunately.

The good news is, I have been able to think a lot about building it, and how I would do that (which sections to build first, second, etc.). I have a pretty good mental picture of how it is going to come together (that is, until something unforeseen occurs, which it probably will). This is a technique I practiced for years as a kid. I would lay in bed at night and mentally design Lego creations, and then the next day I would go build them. I built cars, trucks, castles, spaceships, you name it. The part that I need help with and would like some input on is the physical layout of the electrical system in the available space. So here are some options I am considering:



Option 1:
Pros: Having both batteries on one side keeps the batteries separate from the charger and inverter, so there is less of a chance of having a spark ignite the H2 gas that sometimes develops with charging. I do plan to vent the compartments, but with this, I wouldn't need to worry at all about having possible ignition sources in with the batteries.
Having the batteries close together is good for dual battery systems because the wiring between them can be kept short.
Cons: There would be 90 lbs of battery on one side of the trailer. The charger and inverter might weigh 25 lbs, so the load isn't balanced.

Option 2:
Pros: It solves the side to side weight imbalance by putting one battery on each side.
Cons: There would be other electrical devices in the battery compartments, so I would need to aggressively vent them. I would probably need some computer fans that would push air in/out when the charger or inverter were running.
Having the batteries at the front of the trailer makes the wiring connection between them shorter, but increases tongue weight compared to having them closer to the axle.

Option 3:
Pros: Might be best weight distribution, both side to side and front to back.
Cons: Requires the longest cables to hook everything up. Need some seriously thick cables.
Still has the same issues as option 2 with needing to vent the compartments (batteries and electronics housed together).

Which option looks best to you? Any other ideas I should consider? (Can't put them all in a single compartment across the front of the trailer in this design, and no room on the tongue for a tongue box.) Basic design looks like this:



Thanks!
Lauren

[noseoil]

Lauren, I was going to suggest putting them both together on the center line somewhere toward the front (tongue box would be best by my way of thinking), but it seems you have ruled this one out. That being said, I would still try to have them as close together as possible, so the cable run to the inverter is as short as possible. This will keep wire size down & consolidate the harness you need to make up.

Have you considered hanging them from the bottom side of the bed, close to the center line & just in front of the axle? This would lower the center of gravity, keep the extra mass closer to the middle & in general make things work. The down side is the maintenance factor if they need water & accessibility in general would pretty much stink.

I guess in general I would have to favor choice #3, and run a conduit beneath the floor, so runs are as short as possible for the inverter load. Please make sure to have adequate ventilation for charging & use. I broke down and bought a sealed box with a snoot for venting mine, it's not really worth having corrosive gasses moving around the build which can ignite from a spark.

Sorry about your elbow. My right shoulder is sending me to the PT's office next week, due to the work on my build. Funny, but 25 years ago I didn't have trouble lifting cabinets, walls & panels like I do now..... I'm thinking lifting 5' wide sheets of material isn't the best thing I can do now (baltic birch), so I'll be taking it a bit easier as well. Hell getting old, isn't it?

[rebapuck]

Here is the bed in my former trailer. To make the bed, the table is first stowed in the footwell. Dowels are placed across the footwell (in notches) and the cushions, attached to plywood, are pulled to the center. The back cushions fill in along the wall. The only thing that needs to be stowed is the two dowels. As you can see, the cushions were thick and quite comfortable. I used a sleeping bag in winter, and just a light blanket in warmer months.

[KCStudly]

I thought of the same thing as Noseoil, putting them under. You could make access hatches to service them from above.

Don't forget, you could divide your storage compartments with bulkheads so that the batteries are in their own water proof and vented spaces, while the remainder of the electronics are separated. The TB design I have started building has a separate battery compartment that will be lined with glass/epoxy, and have vents in both the top rear and bottom. The bottom vents will give me the option of hosing out the battery compartment should there be a need.

[lfhoward]

Noseoil, rebapuck, and KCStudly: thank you for your insights!
Re: battery compartments: I like the idea of keeping the load balanced, so I am probably going to go with a variant of option 2 or 3. I bought plastic battery boxes and plan to install vent hoses that go from the top of the boxes to the sides of the trailer. Either that, or wall off the electronics by subdividing the compartments (brilliant idea) and venting the battery side. I considered the suggestion of running the wires through the floor and under the trailer (or putting battery boxes down there), but I'd like not to cut the 1/8 inch steel decking, if I can keep all the camper electrical inside the cabin. Simpler and more waterproof that way. I figure 2 or 4-gauge cables would work for the length I would need (10-12 feet). [correct me if this gauge is not thick enough, please! Don't want it to burn to the ground.]

Re: bed setup: thanks for another good idea. I have several options I am considering now, from convertible folding side benches, to side-out gauchos, to a table-and-cushion setup, to simple, removable, hardwood boards-across-the-benches-with-a-queen-mattress-on-top. Either way, I will have the low benches over the wheel wells and utility compartments to work with/around.

[lfhoward]

Hi Everyone

Thanks for taking the time to respond. Appreciate the electrical advice! Taking what you said into account, I came up with a 4th option.

In this option, I create a 3rd utility cabinet at the center front of the trailer, that is accessible from inside. The two batteries could live next to each other in there, minimizing cable lengths. The rest of the electrical equipment (inverter, charger, shore power inlet, power transfer switch) could all be in a single cabinet on the driver's side. That leaves the cabinet on the passengers side open for hauling stuff, like the camping stove, propane cylinders, lantern, etc.

In order to not have the battery fumes in the cabin, I was thinking of putting the batteries inside plastic battery boxes, with vent tubes running directly from the boxes into vents in the front wall.

The trade off here is 1 foot less floor space inside the trailer when I want to use it as a hauler.

The tongue is reserved for an air conditioning and heating unit.

[lfhoward]

The electrical system for the trailer is beginning to take shape. I got a shipment of parts today that included cables and battery boxes, so I had to give this a try!



It consists of three Group 24, 12 volt Deep Cycle Marine batteries, hooked up in parallel.



I charged each one separately a couple of weeks ago so they are topped off and about as similar in charge as they can get before linking them together. Each battery stores approximately 80-90 amp hours, so the combined battery bank of 3 should net me at least 240 amp hours at 12 volts.

What is that in terms of useful capacity?

Fantastic Fan 3 amps on high
LED lighting 3 amps combined when all on
2 power outlets 15 amps each at max draw for 30 amps
Inverter - about 40 amps at 500 watts
(41.6 amps at 12 V = 4.16 amps at 120 V, for 500 watts of power)

All together = 76 amps, which could run for 3.16 hours.

But there is no way I would use everything all at once!

A more likely scenario:
Fan: 3 amps
Lights: 3 amps
IPad charger: 2 amps
Laptop computer 85 watt charger via inverter: 7 amps
Total = 15 amps

At 15 amps of draw, the 240 amp hour system could last 16 hours, or 5 days at 3.2 hours a day. That's basically what I designed the off-road trailer for: boondocking it where there isn't a place to plug in.

At 6 amps of draw, the system would be good for 40 hours on a charge. That would go much farther.

Ultimately it would be nice to have solar charging, but for now I have a Kussmaul AutoCharge 1000 that runs off of campground or home electricity to charge the system.

[noseoil]

Looks like a plan to me & should be plenty of power for most things. You're right that you won't be using the full capacity of your system all the time, but remember, the battery should only drop to about 50% of it's capacity before being recharged. Any more than this & you're shortening the lifespan significantly & asking for trouble. The inverter will use about 10-15% more power in the conversion process of 12v to 110v, than is actually being consumed. If it's running a 100 watt light bulb, it will take more energy than this due to the "parasitic drag" inherent in the conversion process itself. That having been said, you don't draw 500 watts all the time & it depends on the actual load you're powering. Mine uses a remote switch to turn it on & off. There's no sense in keeping it hot, if there isn't a 110v load being picked up. Charging can be done while in camp with regular shore power, or at home but.....

That's why a lot of people have gone to solar panels as a way of dealing with the charging problem while camping in the boonies. They won't supply a lot of power at one time when they're working, unless you have a large bank of panels, but for LED lighting & relatively small 12v power consumption, they can usually keep up with the demands & give you a battery which can be "topped off" during a full day of sunlight if it isn't too low. It's worth looking into when you have a little time. I grabbed a 100 watt Renogy system from Amazon which will charge my group 27 battery fully in a summer day if the panel is in direct sunlight. Since the roof faces up anyway, it's not a big deal to set up a simple system for charging that runs itself.

This would keep your battery bank topped off and ready when the trailer is just sitting there & waiting for the next trip. Something to think about anyway.

[lfhoward]

Noseoil,

I checked out the Renogy panels you referenced, and wow, they are a good deal! Solar is a lot less expensive than I imagined it would be. It looks like a single 100 watt panel would charge my batteries over a couple of days, but a pair of them would probably do the job in just one day (depending on my electricity usage).

I notice Renogy sells moncrystalline and polycrystalline panels, and a quick Google says they are really close to being the same in terms of output and price these days. Either way, Renogy guarantees them for 25 years! Which style did you get?

Do you have a PWM or MPPT charge controller? From what I read, it sounds like the MPPT one is supposed to be more efficient and keep a better eye on your batteries so as not to overcharge them. Of course, it is more expensive than the simpler PWM charge controller. If you're running a PWM, how does it do?

My plan is to build the trailer next and make it a reality. Then, once it's built (and the budget recovers a bit), I'll mod it with items like a better pure sine wave inverter, solar charging, and an air conditioning & heating unit. Meanwhile, I'll be sure to run 10-12 AWG wires up to the roof where the solar panels will eventually live, so it will be easy to install them when the eventual time comes.

Thanks for your ideas, and for always responding with helpful advice! This is an awesome forum.

Lauren

[lfhoward]

I picked up a 1000 watt (2000 surge) pure sine wave inverter over the weekend. Yay Craigslist!

It's a Xantrex ProWatt SW 1000 with a remote on/off switch that can be mounted inside the trailer.
Here's a pic from the web:



And technical info:
http://www.xantrex.com/power-products/power-inverters/prowatt-sw.aspx

[noseoil]

Hi Lauren, the panel & system I got was the cheap one. It's a poly-crystalline panel & PMW charger combination. Since I'm still "working on things" for the build, I have no idea how it will really work at this point, but it should be fine based on the numbers I ran. I'm thinking the power consumption I use & battery size (group 27 Trojan AGM) should be able to keep things topped off on any given day, if there's some sun. If it's cloudy weather, full shade or anything like this combination for several days, the wiring & charging system from the truck will be another method of keeping the battery topped off. Worst scenario would be to have to run a generator to power up the PD4045 & charge things for a bit.

I was surprised at the (relatively) low cost of a solar system, like you were. For less than $200, a permanent charging system that runs by itself sounds like money well spent to me. Since I was already planning on a battery with lights & a stereo, it wasn't too bad to include room for the system into the build. I've laid out the roof framing to allow for the solar panel mount, wire runs into the top of the shell & a charging module location on the galley bulkhead bear the battery box. Taking as long as I have for my build, there's usually a little extra money floating around if I "need" to put something else in place while I'm crawling along.

Perhaps the "Tucson Snail" might have been a better name for my build.....

[lfhoward]

Noseoil, I like your Tortoise build. It is better to do it the way you want it and take your time, than to rush and have it turn out not as good! And enjoying the designing and building process is what it's all about, I think.

Well, I finally created some sawdust this weekend! I built the wooden foundation/sills that my walls will be built on. The sills are bolted to the steel trailer deck with 22, grade 5, 3/8 diameter bolts, washers, and lock nuts. (Probably overkill, but I am ok with that. The sills are on temporarily, as I will take them off and waterproof seal underneath when the wall is all constructed and ready to reattach for good.)

A closeup of the bolts.


I left 1/4 inch margins for the exterior plywood, which will come right down to the steel deck over the outside of the wall sills.


I drilled out the wood to lay flat over the ridges in the steel deck.


The big picture as of today.

[KCStudly]

Bolt spacing looks right to me.