Wandering Homestead

Since the last post (what, two weeks? Three?), most of my van-related activity has been in pursuit of the electrical system. I figured out a significant portion of it (ahem, the vehicle alternators will charge the house batteries, not through a DC-DC battery-to-battery charger, but rather using a DC-AC-DC system with an additional inverter. Aren’t you glad you asked?), and that decision let many other details fall into place. But the niftiest advance involves the inclusion of computer technology in the van.

I’m a software developer; you were expecting fine woodwork?

In all likelihood, you’ve heard the term “Arduino” bandied about. You might even have an idea what they are. If not, fret not. Arduino is the specification for a family of processor chips. The word also refers to the chips themselves, the concrete manifestations of that standard. Other examples of processor families are the Intel chips found in most PCs, the Apple M-series chips now appearing in new Macintoshes, or the ARM chips powering most cell phones.

One particular configuration of an Arduino chip is the ESP32 board. This is a little circuit board, about 1” x 2”, with an Arduino processor, some memory, a few other chips, and a bunch of pins to which to connect wires. Besides these wired connections (using any of several industry-standard protocols), the boards support WiFi and two flavors of Bluetooth, regular and low-power. They can take inputs from a wide variety of sensors and detectors (temperature, humidity, movement, light, and so on), and drive outputs like relays, little-bitty screens, and speakers. And they cost around $10 apiece.

My first thought about using ESP32 boards was the flexibility they offer. In the van, there are going to be lights and fans and other devices to control, as well as switches and buttons to control them. And a whole bunch of wires crisscrossing the van to connect the controllers with the controlled. So what happens when, two months down the road, we decide that it would be much more convenient to have the switch that controls the galley lighting right here instead of over there? Or two switches, one here and one there. If everything is hard-wired together, making those changes would involve tearing out a lot of stuff and redoing it.

On the other hand, if all of the switches and buttons were just connected to a central computer, which was also connected—through relays and other electronics—to all the lights and fans and such, we could change the behavior of any switch with a simple programming change: five minutes work. With this in mind, I started my research.

Since then, a few more applications have suggested themselves. The house batteries are of a variety (LiFePO4) that should not be charged when cold. They work just fine in the cold, powering all the appliances and devices, but trying to recharge them when they’re near freezing can damage them considerably. What if we had a little stand-alone computer, hooked up to temperature sensors and controlling a little heating pad under the batteries? That would keep them from getting too cold to charge.

Another application would be level detectors for the fresh-water supply and grey-water output tank. With a couple of these, we could always know how much water was left to drink, and how close we are to needing to empty the grey-water tank.

Y’know how a smart phone knows which way it’s pointed, and which direction it’s moving, and how fast? There’s a device inside, a gyroscope/accelerometer, which supplies all that information. It’s tiny. You can get them on Amazon, three for $10. They’re so small, they had to stick them on 1” x 1” cards, just to be big enough to attach the appropriate wires. The ESP32 card can talk to those, as well. I’m still trying to figure out a good application for an accelerometer, but I know there’s one out there. Probably won’t need an alarm to tell us the van is tipping over, but we should be able to think of something.

For the past few weeks (months? Oy), most of my van attention (when not doing general reading and research) has been on the floor. Yeah, some of it has been on the roof rack, which I discovered really should have been put together with stainless steel bolts and nuts. Turns out, rain can get the rack and its hardware all wet. Then the hardware might rust, if you can imagine that. So I’ll need to order new hardware and spend a few hours replacing it all. Whee!

Floor, yes, the floor. From the factory, the van’s floor is fairly thick sheet metal. And it’s filled with many small peaks and valleys, poking above or below the main floor height by about a half-inch. This makes the floor much stronger and less likely to bow than if it were flat. We build our camper’s floor (quite flat) on top of it. From the postings on the forums, it seems most builders like to fill all these valleys with insulation, both thermal and acoustic. Others like to leave them unfilled, to provide some air circulation.

On top of that, some people like to put a thin layer of closed-cell foam, like Minicell, as a moisture barrier and for more acoustic deadening.

Over that layer comes (usually) the main layer of insulation, either:
• XPS (expanded polystyrene, aka Styrofoam),
• XPI (expanded poly-isocyanurate, somewhat higher-tech Styrofoam),
• wool batting (really),
• Thinsulate (same as in gloves and jackets, just thicker),
• or nothing at all (in temperate climes, not much heat is gained or lost through the floor)

The next layer is usually a sub-floor of half-inch plywood, most often Baltic birch or marine-grade. And finally, the layer that people will actually stand on. This can be just about any flooring material one would use in a home or office. There’s much leeway since it probably doesn’t extend under the cabinetry or bed or shower or anyplace else that people don’t walk. This means that very little is needed, so if it’s heavy material, not a such a big deal.

From the possibilities to the actuals: I’ve decided to let the van breathe, and leave the valleys open. I may go in later and put a layer of acoustic insulation in them, but it won’t fill the valleys, just coat their bottoms. That’s step one.

We’re skipping the Minicell layer. Seems to me like all of its functions can be handled by the other layers.

For the main layer of insulation, we’re going with 1.5 inches of Thermax. This is an XPI, with a little fiberglass mixed in, and coated on both sides with aluminum foil. From what I’ve read, it has the best thermal properties, and is fairly easy to work with. The biggest problem is that it’s not a consumer item, and is rather difficult to track down. After several weeks of searching, I found a lumber yard in Ypsilanti that was able to order it specially.

For the sub-floor, I decided on half-inch Okoume plywood. This is very high-quality, marine-grade plywood. The closest place to get it is Charlotte, Michigan. It’s really pretty, which is not an adjective very often applied to plywood.

In order for the sub-floor to fit properly, the underlying insulation really should be in place first, as the profile of the sheet metal floor is slightly different from the profile of 1.5 inches above it. So before I knew just how I’d acquire the Thermax, I decided to make a trial run out of cheap XPS sheets ($15 at Lowe’s). I just won’t permanently affix it, as I will the final insulation, and then I’ll be able to replace the XPS with the Thermax I eventually find. As a bonus, I’ll be able to use the XPS pieces as a template when cutting the Thermax to fit the van.

The incisive amongst you may now be wondering how I cut the XPS in the first place: what did I use for a template then? Good question. Cardboard! To make a template, I first took a bunch of opened-and-flattened cardboard boxes, and cut and arranged and taped the pieces to cover the floor more or less precisely. Then I took up that template, and transferred its shape to new 4’x8’ sheets of pristine cardboard, to make a template I could move around and would not catch and fall apart on all the tape and seams. Then I used that new template to cut out the XPS insulation.

But before I could cut out the plywood sub-flooring, I got a line on the Thermax I’d wanted. So I used the XPS as a stiffer, easier-to-handle template, and used it to cut out both the Thermax and the plywood. Then I covered the plywood—front, back, and edges—with several coats of Polycrylic, to seal it against moisture, so it won’t warp or rot. And here we are.

Right now, the Thermax and plywood are just lying on the floor. It’s a pretty good fit, so they won’t move much, but there are a few more structural additions I’ll make before affixing it all securely (permanently!) to the van’s sheet metal. This has to wait until more of the design is finalized. I’ll discuss their motivations and ramifications then.

Yup, I know. I’ve been remiss in my capacity as chronicler of this van build. You’ve been waiting (some more patiently than others), but I’ve been sitting on my hands. And while I knew that neither Elizabeth nor I had posted in a long time, I didn’t realize that the last post was before we got the van.

We did.

It’s here.

Big and beautiful.

We picked it up on Tuesday 20 July 2021. First thing off the lot, we took it to a truck scale. With a reasonably full gas tank and two occupants, it tips the scales at 6320 pounds. We’ll see what happens to that number as the build progresses.

The pictures above are taken somewhat after that. I had already built and installed the roof rack, as you can see. The rack itself is made of a product called 8020 aluminum extrusion. It’s made by a company called 8020, as well as a few others. I discovered it early this year, while learning how to build this beast. The 8020.net website bills their product as an Industrial-Strength Erector Set. The funny thing is, that’s exactly what I had called it, once I realized what could be done with it, but before I’d visited the site.

Besides the roof rack, the plan is to build all of the van’s interior components (galley, shower, bed/table frame, and so on) as separate modules, framed in 8020, and therefore moveable, removable, and modifiable, with considerably less effort than if they were built of wood or some other material. I could spend many pages discussing the properties of 8020, what can be done with it, and how to work with it. But that’s not the point of this blog. If it interests you, I encourage you to look at 8020.net. It’s really cool stuff, and there’s lots of information there.

If you’ve been paying attention, you’ll recall that when we ordered our van back in February, we were told it would be delivered during the week of May 24. And if you’re awake, you’ll note that that week has come and gone. In lieu of a shiny new van awaiting camperization, we have a new target date: the week of June 25. That’s next week. Fingers are crossed.

In the mean time, we’re stilling pounding away on this project. Do you know what this is?

To give a little context, the room is our dining room, from which most of the furniture has been relocated. We’ve taped off the floor to represent the interior of the van, and are laying out mock-ups of the major items that will be in it. This particular rectangle we’ve constructed out of old cardboard and 1×2 lumber as a representation of our bathroom/shower. It occupies a 2′ by 3′ space on the floor, and gives us a feel for the eventual proportions of the finished room. That cardboard box in its corner represents the composting toilet, which we’ll keep in the shower. There will be a thin scrolling door, closing the shower from the rest of the van, that squeegees off all the excess moisture as it’s opened.

And this is a model of the frame in which our refrigerator will reside.

The frame is made of old scrap lumber we happened to have in the basement. It’s just about the height of the interior of the van (or what it will be when the insulated floor and ceiling are installed). The cardboard panel is the refrigerator door within the frame, with marker lines separating the freezer above from the fridge below. We can move the cardboard up and down to find the right height for us, with storage both above and below it.

We also have various 3D cardboard rectangles to represent the water heater, propane locker, batteries, and whatnot. As we construct the larger items, we’ll populate them with the smaller ones, to get a feel for how space will be used.

Which brings us to the latest addition:

We ran out of long scrap wood, so I bought some 2 x 4s, ripped them down to 2 x 2s, and started screwing them together. This structure, in its eventual incarnation, will be our bed, dining area, and storage compartments, with room for dog crate(s). The closed rectangles will have wooden tops. When we want the bed, we’ll fill the open rectangle with slats, and cover the whole thing with a queen-size memory-foam mattress. In the dining configuration, the mattress will fold up into cushions, the slats will come out to let our feet dangle in the open area, and that box in the open area will be a raised floor on which to rest our feet and mount the support for our table top. With, of course, more storage below.

The first thing I noticed when I put it all together is that it’s too tall. In planning, I’d wanted the mattress to be at about the level of the van’s widest point, or about 31 inches off the floor. We plan on sleeping east-west (side-to-side within the van), and want our bed to be as long as possible. There’s even a Post-It note on the refrigerator door, above, with the right measurements. But for some reason, when cutting the lumber, I kept thinking of the desired height as 36 inches. Nor did I account for the thickness of the mattress. Sigh. That’s why we’re mocking everything up in cardboard and wood before committing to the eventual materials: to make our mistakes while it’s still cheap.

So today’s project is to lop about six inches off all those uprights, and see what we get. Stay tuned.