Stealth Camper Build Thread

[Ran D. St. Clair]

In The Interest of Full Product Testing…

You asked for it, so I gave my all, and now my eyes are blue again. Must be a quart low…

Actually, after some considerations I decided that I needed an actual poop test. Primarily, I wanted to know exactly how much and how bad it was going to smell for those who might be in the neighborhood. I was also unhappy with how warm the outer shell of the exhaust pipe became. It was not hot enough to burn anyone, but I didn’t like the idea of dumping that much heat into my air conditioned living quarters.

No, I did not park my arse on it while in the driveway. I will leave it to your imagination how the deed was done, but suffice it to say that one actual turd was harmed in the making of this review.

I got a length of 4” diameter steel single walled ducting and then insulated it with 1” of fiberglass mat held on with aluminum duct tape. I then inserted it inside the existing 6” exhaust pipe, which is further insulated and surrounded by an 8” outer pipe. That makes the chimney a consistent 4” inside diameter almost 7 feet above ground level. It also provides 2” of insulation all around with an infra red reflective layer in the middle.

I started the test, as before, with a ½ cup (of water) urine cycle, just to warm things up and to be consistent with the previous test. After about 15 minutes it was complete and nothing anywhere was more than slightly warm. The outer wall of the chimney was pretty much dead cold.

The actual poop and associated urine was placed in the bowl with no paper liner this time. I attempted to use the dual spray nozzles built into the bowl to wash down a few splatters, but they were ineffectual. I might be able to adjust their aim to help the situation, but at this point I think they are there mostly for show. The lid was closed and a waste cycle was initiated and the burn proceeded for about 45 minutes as expected.

During the initial phases of the burn there were some slight whiffs of unpleasant odor, similar in degree to the previous experience with wet bread, but of course it didn’t smell like toast. It didn’t smell like raw poop either, though I won’t claim that it was a nice smell. After about 15 minutes the poop must have been desiccated and started to burn because the character of the occasional whiffs changed. It became somewhat earthy and toasty and dare I say almost pleasant. By 30 minutes there was little if any detectable smell. As before, there was never any visible smoke, only heat shimmer.

I do not believe any of this would be detectable inside the living quarters, but there is no way for me to actually know that until it is properly mounted inside the truck. Until then, I will have to assume that the slight positive pressure inside the toilet housing in combination with the chimney draft will drive any smells up the exhaust pipe.

After the cycle was complete I was able to open the lid. As you might imagine, the auger was smeared with a thin layer and a couple of small globs of poop. The thin layer was completely desiccated by the radiant heat and airflow from the burn, though the small glob was not. Nevertheless, there was no detectable smell, only the unsightly smear. See the images provided under keyword “Stealth”.

The new chimney design worked perfectly. After the waste burn was complete the outside of the chimney pipe was only slightly warm.

Several hours later the whole thing was cool enough to examine the fire box for ash. I found one flattened charcoal lump about 3” in length, and a small amount of loose granular ash. As before I had to lightly scrape the bottom of the burn chamber to release the lump. It appeared more completely burned than the bread, and also of lesser volume. It appears poop doesn’t hold up to flame as well as wet bread. Naturally, it was completely desiccated and sterile. I am now reasonably assured that the fire box can hold a month or more worth of this kind of ash before it will need to be cleaned.

I think this completes my pre-installation testing. As much as you guys would like to see my lily white backside on the toilet, my son refuses to take the picture so you will just have to use your imagination.

To be Continued…

[geofkaye]

FUNNY as it seems: .....one of the major factors that people want is a toilet that works every time with NO odor with little or/NO cleaning- every rebuild that I have ever done-we have spent more time on this issue than anything else. Ran D. you are a true engineer and have proved that you think as one...wish you were closer and I could add your insight and intellectual curiosity to our company when we have a problem that needs engineering guidance....from my experience-messing with toilets, I have found that if the exhaust pipe is open at the bottom and the top there seems to not be an odor problem even in a windy parking lot/campground....I use a 4 inch schedule 40 plastic pipe with a "wye fitting" midway for the toilet to exhaust odor and any fumes.....geofkaye and the Rivercity girlz that would test the toilet in the driveway under real world conditions with real world poops......[girls are used to jail anyway]

[Bob86ZZ4]

Good job. What about maybe installing a spray hose near the toilet in the truck. Then you could wash it easier? Don't some rv toilets have a wash down sprayer next to them? I've only owned two rv's and neither of mine had one but I think I've seen some that do.

[Ran D. St. Clair]

Thanks guys...

I don't think I can wash it down with a heavy spray, like a garden hose, as there is no where for the water to come out. I would have to boil it out, and it would probably only hold a gallon or so at most. I know this is common practice for conventional toilets with black water tanks underneath, but those tanks are much larger than my fire box.

I am thinking that I could just keep a spray bottle on hand near the toilet. That way I could direct the spray as necessary and it wouldn't add to the liquid content by more than a few tablespoons.

I am not sure what would be compatible with the metal of the firebox. but I am guessing that a tablespoon of bleach or a tablespoon of lemon juice in the spray bottle might help get the job done without hurting anything.

Push come to shove, the toilet bowl pops right out and can be cleaned with a paper towel. As for the dry brown smear on the auger, as long as it doesn't smell I can just close the lid and live with it. I realize that the sight of it would gross some people out, and make this design unacceptable in some peoples eyes, but I am very much a pragmatist, especially in this application.

[BUonM22?]

You're forgetting the tablespoon of lacquer thinner mixed in with the bleach and lemon juice... ignite that and it'd take care of it in a few seconds :-) Plus lacquer thinner cleans like crazy, evaporates quickly, and once you use it enough... a zingy aroma as well.

[Ran D. St. Clair]

One More Toilet Mod

I hesitate to mention this, because I am not sure if it was worth the effort, but I wasn’t happy with the idea of digging out a bunch of mineral wool every time I needed to vacuum the ash out the burn chamber. The mineral wool itself is fluffy, like heavy cotton balls, and I am pretty sure it will gradually get lost, and dirty, and blown away by the wind, as I pull it out and put it back in time after time. I was also worried that it was itchy and slightly bad for you, like fiberglass insulation, though I must admit, after working with it a bit, it doesn’t seem to be.

My idea was to define the opening to the fire box plug with a layer of high temperature silicone, and then further create an insulated plug of mineral wool and high temperature silicone. The idea ultimately worked, but it was not easy to do.

I began by opening the fire box access doors, and removing mineral wool to access the plug. I then removed the plug and taped over the opening with scotch tape to protect the internal threads. I then shaped the mineral wool around the opening to allow access to the plug including room for my fingers to grab onto the plug.

The original plan was to just smear a layer of silicone onto the surface of the mineral wool. That plan lasted about 30 seconds as I quickly had silicone all over my hands with nothing stuck to the mineral wool. I then found that I could force the silicone onto the surface of the mineral wool with the caulking gun by laying down successive beads, much like piping frosting onto a cake. This only worked for surfaces from horizontal to near vertical as the mineral wool wasn’t strong enough to hold the silicone against the pull of gravity. I then tried laying pieces of fiberglass cloth into the wet silicone, which worked fine as long as I only touched the dry side of the cloth. I then found I could apply the silicone to the cloth and then press the cloth into place against the mineral wool. The trick is to not get too fussy and try to work it too much. As soon as you get silicone on to your fingers or whatever tools you are using they get sticky and it is time to stop.

After the silicone was cured I was able to go back over the surface of the cloth with a layer of smeared silicone. At this point I could also make a good seal around the access pipe and to some degree around the opening to the sliding metal door in the outer fire box. The trick here was to avoid jamming the door slide with silicon. Fortunately the silicone remains fairly soft after it is cured and can be scrapped away if necessary. When everything was cured I removed the protective tape and installed the metal screw plug.

The making of the silicone plug required a different technique. I started with a large ziploc bag with the top Ziploc portion removed. I then filled it with the mineral wool that I had removed from the fire box, wrapped it up tight and pushed it into the opening on top of the screw plug. I mashed it into place and closed the sliding door behind it just to make sure it would fit. I then gently took the bag out again which allowed the mineral wool to hold the rough shape of the plug.

This next bit is tricky. I opened the bag but left the mineral wool plug deeply seated in the bag. I then piped heavy beads of silicon on top of the mineral wool while it was still in the bag. I couldn’t get to all sides of the mineral wool but I was able to cover about 2/3ds of it. Then I wrapped up the bag tight and shoved it back into the opening behind the sliding metal outer fire box door.

Normally the silicone would set up in 24 hours, but the bag was preventing a free flow of air so it was setting up more slowly. After 24 hours I was able to open the sliding door and open the back of the bag just enough to let some air in. The silicone in that area was partly set at least enough to hold its shape roughly, and even if it had distorted a bit it wouldn’t matter because the whole thing is spongy and meant to conform to whatever space it is forced into. After a few more days the silicone was set all around and I could remove the partly formed plug.

I then opened the bag and added a heavy layer of silicone to the exposed mineral wool areas just like before, then wrapped up the bag and stuck it back into the opening to cure. When it was partly cured I opened the back of the bag just like before. After it was fully cured I removed it from the bag and I had my fully formed plug, but it was all wrinkly and ugly from the folds in the bag. I could now trim off any unwanted silicone with scissors and then smear on a final layer of silicone to smooth things out and make it look nice. Finally I baked it for a couple of hours in a 350 degree oven just to make sure the silicone was fully cured.

The end result is a custom fitted silicone bag full of mineral wool. Will it hold up to many years of use? Ask me several years from now…. I have installed it and removed it several times now, and so far so good. A picture is available under keyword “Stealth”.

To be continued….

[Ran D. St. Clair]

Sunfrost RF-12 Refrigerator Impressions

I recently Received my Sunfrost RF-12 refrigerator. I really like the refrigerator, but I can’t say much for the service I received from the altE store, altEstore.com.

I ordered the refrigerator on 8/25/09. I paid top dollar, $2,342 for the fridge, $50 crating fee, $160 Shipping, and $236 in sales tax, for a total of $2,788. They called me back immediately to confirm color, what side the door was to be hinged on, etc. So far so good.

On 8/31 I received an E-mail indicating that my refrigerator was ready to ship. On 9/1 I reconfirmed what side I wanted it hinged on and was told that the refrigerator would ship that same day. So far so good.

I was in no rush, so I didn’t call them back until 9/18 to let them know I hadn’t seen my refrigerator. That’s when they handed me off to the customer service department. It took the customer service department at altE until 9/21 to get back to me and tell me that my refrigerator would be ready to ship between 10/2 and 10/9. On 10/12 I contacted them again and was told that my refrigerator would be ready to ship in the next week or two (10/19 to 10/26). It actually arrived on 10/19.

I was never in any rush, and I don’t mind the delay, but I don’t like being lied to. Unfortunately I don’t know who was lying, Sunfrost or altE. The good news is that I now have the refrigerator and it looks and works fine.

It came very nicely crated, on a new pallet with a cardboard box over the top. The corners were reinforced, and the top had a diagonal wood brace to prevent crushing. It was well labeled and obviously well made. I know, I am gushing about a packaging job, but I paid $50 for that package, and more importantly it helps to give me a sense for their attention to detail.

The refrigerator itself is also nicely made. I immediately liked the clean and simple design approach. It appears to be a heavy plywood box with Formica and aluminum extrusions in the high wear areas. The hinge is a full length heavy duty stainless steel piano hinge. The hinge line is flush with the outside edge, in my case on the left side. The doors are so thick you need at least 4” of clearance on the left side of the hinge forward of the hinge line. In other words the doors need to stand proud of any cabinet walls in order to have room to open.

It’s very boxy with sharp corners, rather short, and wide. The short part is because it is meant to be mounted on a cabinet about 2 feet tall, which is more or less what I intend to do. I assume that the shape is a concession to efficiency. A square box has the least surface area per volume, at least for something with flat sides. The insulated walls are also very thick, adding to the width. Likewise the doors are very thick, and the walls around the freezer are even thicker. It has 8.07 cubic feet of internal space plus 2.05 cubic feet in the freezer, so it is not a really small refrigerator.

The compressor and radiator are all on top of the unit, just like they were 100 years ago when they first started making refrigerators, and for the same reason. Heat rises, and it makes no sense to put something hot under a refrigerator. The mechanics are mostly hidden behind a short fascia on the front and sides. I really like the way it is all right there, simple and accessible. It does require a minimum of 6” clear space above the refrigerator for proper airflow though.

They make them for 110V operation, but this one will automatically adapt to run on either 12V or 24V DC. The compressor is a conventional looking jelly bean shape, though on the small side, like you would expect for a tiny under the counter refrigerator. It is made by Danfoss and comes with its own manual, which I like because it has some nice technical details like fluid pressure, schematics, alternate circuits, etc.

It’s very quiet, with the loudest noise coming from the boiling of the internal coolant.

The manual for the refrigerator itself is short but complete. There isn’t much you need to know about a refrigerator that we don’t all already know from long experience. They do make a few interesting points though. For example, the compressor will automatically refuse to start for several minutes after it has been shut down to minimize the pressure difference and the starting load on the motor.

The external wiring has to be up to the task, but it only draws about 4.3 amps when the compressor is running. That's just 52 watts running flat out. It shouldn't have to run very often with all that insulation, so it really is very efficient. The thermostat actually controls the refrigerator temperature with the freezer a roughly fixed amount colder. Even that can be adjusted by changing the quantity of coolant in the system.

I powered it up with 12V and put an ice cube tray in the freezer. I was pleasantly surprised to find it frozen solid about 6 hours later. Usually, in my experience, it takes a while for a refrigerator to chill all of its internal mass before it can really chill what is inside. It was all but empty at the time, but I am still glad to see that it can make ice with authority.

I only have one small complaint about the refrigerator itself, at least thus far. The internal light is very dim. So dim that I suspect that they gave me a 24V bulb. They were supposed to give me both a 12V and 24V bulb, but I only got the one. Actually the idea of an incandescent bulb in a high efficiency refrigerator is contradictory to begin with. I will soon replace it with several LED’s that will use less current, make considerably more light, and never burn out.

They claim that this refrigerator is actually better for storing food than conventional refrigerators because it maintains a more humid internal environment that avoids wilting and freezer burn. I don’t know if it’s true, but it would not surprise me given the excellent insulation.

It may be a low volume craftsman built product, but they did a nice job. I like it.

To be continued…

In the interest of fairness I will publish here the complete response I received from the AltE store in response to the above...

Hi Ran,

I wanted to respond to your impression of our service that was reported on a recent survey that you took after you received your recent order from AltE. I also want to say thank you for taking the time to let us know about how we did since we feel that all feedback is important, and it helps us to learn and grow.

You noted that you submitted your Web order on August 25, 2009, and you were contacted shortly after that with a shipping cost to ship your refrigerator, and that you agreed to this cost. You were again contacted within a few days asking additional questions about your refrigerator, confirmation that the color should be white, and asking what side the hinge should be on. At that point it was suggested that your unit was ready to ship. Unfortunately this was incorrect information, to which we apologize for providing. The representative that communicated with you at that point was not aware that these refrigerators are built to order and from the time of order, there is a 6-8 week lead time. The staff has been updated with accurate information about this product, and I noted that the information is also available on our website for folks that order through our website.

You mentioned that you did not hear from us again, and that you contacted us again until September 18, 2009 with no response until September 21, 2009. I would like to mention that I did research your correspondence and discovered the time stamp on your incoming email was September 18, 2009 at 7:09 P.M. Unfortunately our support staff is gone for the day at that time, our normal hours end at 7 P.M. E.S.T. This being a weekend, your email sat in the inbox until Monday September 21, 2009. The lack of response at this point was not due to negligence, but the fact that our store was closed.

Our office opens at 9 A.M. E.S.T. and Gaby has provided me with an email that she sent to you at 9:32 A.M. on Monday September 21, 2009, stating that your request for an update was turned over to our Support team, and you would hear back as soon as possible. Jose has also provided me with a response to your question about when your order would ship, that was sent to you at 4:06 P.M. In his email he updated you with an approximate ship date that he had received from Sun Frost just that day. Sun-Frost representatives gave us an estimated ship date, somewhere between October 2 and 9, 2009. I also see that another correspondence was sent to you on October 12, after you requested an additional update when you still did not receive any news. We should have followed up again with Sun-Frost around the second of October for a firm date and we dropped the ball here. Had we done that you would not have had the need to email us again for another update.

I would also like to say that we provided information to you based on the information that we received from the manufacturer. The estimated ship dates are based on their production lines at the time they receive an order. Unfortunately as we all know, manufacturers do run into unplanned obstacles that occur after production begins that can delay orders. In this industry it is often more frequent then we would like, but a fact. We have learned that it is important not to overpromise information to our customers, and also that we should be following up diligently so that we can remain proactive with information to our customers, and not reactive.

Overall, it sounds like you are completely satisfied with your product, and that is good news! Sun-Frost makes a good product and we have many satisfied customers that have purchased their product.

Hopefully we will learn from this situation, and move on in an effort to do our job better, and hopefully retain a good customer!

Kind Regards,

LuAnn Mattson
Operations Manager
AltE®
Making Renewable Do-able™
www.altEstore.com

[geofkaye]

.....$2788 OR $159+$17......THAT IS A HELL OF A REFRIGERATOR....geofkaye

[Ran D. St. Clair]

Originally posted by geofkaye:
.....$2788 OR $159+$17......THAT IS A HELL OF A REFRIGERATOR....geofkaye

Yes it certainly is... Low volume + American Made = High Cost

We all love to bash the Chinese for putting us out of work, but we sure don't like the high price of supporting our local manufacturing. I'm not claiming the moral high ground or anything though. I paid the price because it was the only way I could find to get what I wanted, a really efficient full blown refrigerator with freezer. Most people would probably make the entirely rational decision that you can buy a lot of energy with the money you save buying a mass produced unit. If you are getting that energy cheap from the grid then this refrigerator makes no sense at all. Give it 10 years though, when the price of electricity quadruples, and you will see highly efficient appliances like this in every store, and much cheaper (relatively speaking) because they will be produced in volume and not a specialty item.

[geofkaye]

.....compare with WOOD's Brands-AMERICAN AND CANADIAN MADE!.......I can not justify anything that expensive for cold/frozen food. I saw a demo at the MOTHER EARTH EXPO in the Carolina's several years ago there they radically changed the usage numbers by just gluing on some polyiso foam board [OR Dow Blue Board and covered with with a layer of that MYLAR silver film from NASA Missions.....COSTS ABOUT $20.00 To achieve the same numbers as Sunfrost IIRC......have to look up the exact numbers some day....I know that most of the refrigeration used in the home is wasted on storage of stuff that is not really in need of refrigeration.....I reduced my cubic foot of refrigeration at home by 2/3 when I went to a new refrigerator[11cuft.] and i think it costs about twenty cents a day in juice.....maybe just a little more now....our juice costs about 11 cents a kilowatt hour.....the dam dehumidifier takes more juice than cooling the food now....wish there was a way of making that cheaper....I'm still running about $100 a month for uitilitys with the super insulation and other non drastic methods of saving fuel....My usage in the Rv isn't enough to worry about....most of my variable costs are fuel and eating out with the girlz....

[Ran D. St. Clair]

I have a crush on foam

My plan for the floor is to put ½” R-MAXX foam board on top of the original wood truck bed, and then ½” plywood on top of that. It’s not as much insulation as the walls or ceiling, but I figure heat rises, so it should be enough to keep the heat in when it is cold out. I suppose it might not be so good for keeping the cold in, like when I am parked over hot pavement or when the generator is running and dumping a lot of hot air under the floor of the truck bed. Then again the floor is 1 ½” of wood, followed by ½” of R-MAXX, Followed by ½” of plywood, and then vinyl flooring. Some of those things aren’t the best insulators, but it all adds up.

I plan to lay down ½” by 2” strips wherever the plywood joins, and also around any openings in the floor, like the safe, or the air inlet registers. I will also lay such a platform under the flooring under the toilet, but for the most part the plywood flooring will float on top of the foam. I figure the foam can crush or deform a bit to accommodate the irregularities in the original truck flooring and give me a relatively flat floor without a lot of filling or sanding.

One concern is whether the foam will stand up to the long term pressure of me and everything else in the truck trying to crush it flat. To alleviate that concern I took a chunk of scrap foam that happened to be about 1 foot square and carefully measured it for thickness with calipers. Now foam is springy and hard to measure so I made 50 or so measurements around the outside edge and put the data in a spreadsheet.

I then placed the foam flat on the kitchen floor with a chunk of ½” plywood about 18” square on top. I then jumped up and down on it for a while, taking care to keep my weight centered on the plywood and foam sandwich. I am sure I could crush the edges of the foam if I were to point load it but I wanted to see if it could handle the distributed load.

I then made another 50 or so measurements around the outside edge of the foam with the calipers and entered the data. It’s not a long term test, but the results are encouraging. After the test the foam was slightly thicker (obviously not) but there was no measurable crushing. The foam does seem to vary in thickness quite a lot just as it comes from the factory though.

I think I can reasonably move forward with my flooring plan.

To be Continued…

[Doc Weaver]

I figure heat rises, so it should be enough to keep the heat in when it is cold out

You would be surprised how cold that floor can get. That was the biggest shock of my first trip. When I got back home, I doubled the insulation (foam rubber)under the carpet.

Doc Weaver

[Radman]

I agree with Doc.

The step area in our coach was not fully insulated and it was amazing how much cold air permeated the area. I have since sealed it up and added extra insulation in the area.

A fun footnote here, I used “foam in place” packing bags that we use at work. These are the packets you break the bags of the two parts to activate the packing foam. The foam is encapsulated in a bag and expands to provide a custom formed packing insert. In your coach the foam expands inside the plastic bag and forms to the contents of the area of your coach that your trying to insulate.

These are ideal to close off areas that are somewhat inaccessible to the standard methods of placing rigid foam. They work when you cant or don’t have the ability to use spray in place foam products and stay tightly in place. I still use an aluminum sheet and some aluminum tape to protect the foam bags from the elements.

Just a thought for those areas that you may have missed during the build process...

Rad

[geofkaye]

...huummm...cold floor and my old bare feet....cheap is 2 layers 7/16'' of carpet pad 8# with a plastic layer on the outside to slow down the moisture...expensive and best way is the R-Maxx...sheet foam.....best way is to spray foam on underside of truck bed....forgetaboutit and use the R-Maxx where you need it!...dam I hate cold floors in the morning.....moisture will form under the insulation if it is not sealed down....i'd suggest a layer of carpet glue first-then foam board...then carpet pad/flooring-whatever you perfer.......geofkaye

[Ran D. St. Clair]

Inverter and Power Supply Installation…

The first step was to install the ½” watertight non-metallic conduit from the generator bay to the inverter and power supply bay. It carries what amounts to a heavy duty 3 wire extension cord that brings 120V AC from the generator to the DC Power Supply / Battery Charger and only to the DC Power Supply / Battery Charger (PS). The battery charger is rated at 90A DC so it only requires about 11A AC, and the extension cord is only about 14’ long, but I still used 12AWG wire. I mounted a plastic box on the back of the inverter and PS bay and used standard home electrical stuff including a 3 prong outlet, front plate, etc. I did put a gasket between the electrical box and the back wall of the inverter and power supply bay, just to keep it water tight. Since all this is exposed on the underside of the truck I don’t want tire splash or dust getting into the electrical bays. I also took some advice from Geofkaye and attached a Velcro strap to the center screw on the face plate to tie the plug into the socket.

I thought long and hard about how to provide adequate cooling to the inverter and battery charger. They both have built in fans and will generate a fair bit of heat over time, especially if they are both working at maximum capacity like on a hot day with the AC running, microwave, etc. I could have just mounted them inside the underbed bay, which is essentially a steel box about 2’ cube. There might be enough exposed surface area on the outside of the box to transfer the heat out, but I didn’t want to take the chance. I decided that I wanted to manage the air flow so the inverter and PS would get cool filtered outside inlet air and then exhaust cleanly out of the bay with a minimum of backpressure. That implies large air inlets and exits with louvers, screens, filters, and other provisions to prevent tire sling and dust from getting into the electronics.

I also wanted to make some provisions to shock mount the electronics and hopefully reduce some of the beating it would take over time. On top of everything else, I wanted to give due consideration to access and maintainability. Filters have to be accessible and washable without tearing the whole thing apart. All of the equipment has to be easy to mount and dismount with a minimum of order of operations dependencies, etc. For example, the rear mounting tabs for the inverter and PS are slotted so they just slide in under the screw heads while the front screws lock them into place.

I ended up with a simple 3 shelf design, but the devil is in the details. An opening was cut in the back wall of the bay with 4 each 10-32 studs mounted sticking out the back (towards the underside of the truck). The filter box was made using a off the shelf louver 5” x 15” with the openings to the rear to shed water while driving. The filter is general purpose washable random strand plastic filaments about ¾” thick, with an additional layer of aluminum screen of the sort you would use in a screen door. If that doesn’t block the fine dust sufficiently then I have enough area to add a single layer paper filter as well. Access to replace and clean the filter is from under the truck but I figured that was easier than ripping out all the electronics to get access from the inside of the electronics bay.

The air inlet filter boxes are made from a couple of standard 12” by 4” plastic floor registers cut down to ¾” thick, with most of the outer rim removed. The inner portion that slides to adjust the airflow was removed as well. These were filled with the same random strand plastic filter material and backed with a layer of screen. They screw into the side of the bay with 4 each 10-32 screws.

The frame for the shelves is 1” by 1/8” hot rolled steel, welded into the metal bay. The bottom shelf is 2” above the bottom of the box to keep it well clear of any water that should somehow get in, either from the small drain holes, or via condensation. I used some recycled 7/16” FRP (Fiberglass Reinforced Plywood) for the shelves. The mounting plates for the Inverter and PS are made from .06” aluminum recycled from the original side doors. They are glued to a 1” thick layer of EPP (Expanded Poly-Propylene open cell foam, commonly used as packing foam in high end applications.) The EPP is glued to the aluminum mounting plate and the FRP shelf using Goop (AKA Eastman 6000). I cut some holes in the EPP to reduce its stiffness and give my electronics a bit of a softer ride. There are also some small nylon straps that loop loosely over the electronics to keep them from bouncing and ripping their base plates up off the foam.

The inverter and PS are both oriented on their respective shelves so they draw air in the front and push it out the back. In order to insure that the exhaust air doesn’t just recirculate back to the input I needed to seal the inner cabinet with lots of high density weather stripping. I also need easy access to all the various wires and cables going in and out so I made the entire side wall removable. When it is closed everything is nicely protected and the remainder of the bay is available for storage. Since the bay door already has a rubber seal all around it wasn’t necessary to duct the air from the inlet filters. I will need to make sure that door is reasonably well sealed though. It’s not high pressure or anything, but I don’t want to be drawing in dust around my inlet filters.

Here’s quick run down on all the wiring. I already discussed the 120V AC path into the bay. I dropped 4 pieces of ½” non metallic conduit into the inverter and PS bay from the inside of the right side outer wall. That should be plenty of wire path for two 120V AC circuits, 12V DC, 24V DC and some low voltage low current control wiring. I ran two short runs of non-metallic water tight 3/4” conduit from the inverter bay to the battery bay which is the next bay over, about 4” away. They will carry the very heavy wires (about 200A maximum) from the batteries to the inverter. Note that the batteries are in their own heavy duty steel box that is separate from the electronics. There shouldn’t be any acid fumes or hydrogen out gassing from sealed AGM (absorbent glass matt) batteries, but they are isolated just to be safe. That just leaves the heavy duty (90A) wires from the battery charger to the inverter (and then via the heavier wires to the batteries of course). They only run about 10” as the PS is on the shelf above the inverter.

The top shelf is mostly just a space to keep the wires organized but it also provides a place for the small 12V DC power supply that sits electrically on top of the 12V from the batteries to provide 24V. It is not very large or heavy, so it is just attached to the shelf with some sticky back Velcro. There is a small sheet metal front panel to close this top opening except that it has two apposing layers of high density weather strip which act as an airtight seal and a strain relief for the 12V, 24V, and control wires that need to exit the sealed inner cabinet.

I should note that I am not intending to use the truck chassis or any part of the box to carry DC ground return current. I will just run 12V power and ground return wires everywhere they need to go, much as you would for hot neutral and ground wires for AC power. The inverter chassis will be grounded to the truck chassis, which implies that the generator will be grounded to the truck chassis through the AC cord between them, but mostly the truck chassis just floats relative to earth ground. If I provide shore power to the Battery Charger / Power Supply instead of from the on board generator, then the PS will effectively isolate the entire truck from shore power, so I don’t think it will matter if the shore power has hot and neutral reversed or not. There is no direct path from any AC input to the chassis, and therefore no way to generate a potential between the chassis and mother earth. After it’s all wired I will have to test that assumption, but for now, that’s the plan.

It doesn’t sound like much but this all took me about 5 very full days to design and build. Now that I have a clear understanding of where the AC and DC wiring enter the living space I can finalize all the wiring inside the walls.

As always pictures are available under keyword “Stealth”.

To be continued…

[Ran D. St. Clair]

It’s all Blizz’s fault…

Back on page 10 Blizz pointed out that Lowes has 20” gas ranges for about $350. I was poking around Fry’s the other day and found a similar unit from Amana, model number AGG222VDW0, for just shy of $400. It was obviously better made than the RV specific unit I already bought and cheaper too. After a week of hemming and hawing I decided that I haven’t spent enough money on this project and bought it.

One of the advantages of buying locally Is that they delivered it direct to my house on a Saturday morning. Picking it up myself wasn’t an option and delivery cost $25 though.

My first impression was that some engineer spent some serious time on a shaker table figuring out how to ship this thing without damage. They did a really impressive job with custom engineered cardboard stiffeners, pads in the doors, and a full hermetic plastic wrap.

Overall, it is an inexpensive range. Compared to the various middle and high end ranges you can find in your local home improvement store it is definitely near the bottom of the line, intended for a small apartment or similar low cost application. It is still a cut above the RV style range I bought though. I don’t say that based on extensive testing or anything, mostly just based on first impressions. The burners are cast aluminum with a cast iron top cap instead of stamped aluminum. The gas valve knobs have a more solid feel, don’t wobble around when you turn them, and don’t hang up when you try to press and turn them. It includes various features that you would “assume” as a minimum for a home unit, like electronic ignition, a window in the oven door, an inside oven light, and a generally better fit and finish.

I like the fact that it is a free standing range. It will simply fit into a gap in the counter top, and if I ever need to buy another one they are widely available in the 20” size so it will just drop right in. I will be able to fasten it securely to the floor and then not worry about custom fitting the counter around it.

It has a broiler below the oven, that I will probably never use, so that might be considered a waste of space. I might be able to store pots and pans in there, as long as they are only metal, but I probably won’t.

It’s not all good though. They included instructions for converting it to propane (which is good) and they intended to give me the replacement jets to make it happen, but instead of the 4 burner jets I needed they gave me 3 and one of those was the wrong size. Fortunately I was able to fill two of the larger jets intended for natural gas with solder and then drill them out to the correct size. I shouldn’t have to mess with this stuff, and I assume they would have given me the correct jets if I had asked, but I have no time to deal with customer service, not when I can just fix it myself. Other than that, the conversion to propane was simple enough There is one somewhat special tool required to convert the regulator, but I was able to get it done with the end of a file that happened to be about the right size.

They provide a nice anti-tip bracket that is bolted to the floor and is supposed to capture the rear feet when it is slid into place. The problem is, they were supposed to give me two of them, one each for the two back feet, but they only gave me one. What I really need is 4, one for each leg, so I will have to poke around on line and see what I can find. As a manufacturing guy it is disappointing when they build an entire product, and get it pretty much right, and then mess up with the simple stuff, like forgetting the accessories.

I plugged the range into 120V AC and hooked it up to a propane tank to test it. It works exactly as you might expect. I found the flame adjustment on the knobs to be very non-linear. The flame is low for most of the knobs travel and then goes from low to full on in the last 1/8th of a turn. It’s not impossible to get a middle setting, but it takes more attention than it should. Also, part of the conversion to propane involves adjusting the lowest level flame on the burners. I ended up fully closing the adjustment screws to get the lowest possible setting, which was pretty much good enough, but it is worrisome to be at the end of adjustment range.

The oven uses an electric glow igniter which draws about 3.07A at 120V AC. That might not sound like much but it is 368W which is a lot. Fortunately it is only on when the oven flame is on, so it probably would not be on for more than about 10 minutes total while baking for over ½ hour, but It’s still a lot of wasted energy. I understand that it’s a safety consideration. They want to make darned sure that the oven doesn’t release propane without ignition. A more expensive solution would have been to use a spark igniter with a feedback loop to turn the gas off if it doesn’t light right away. In a home application the electricity used would be pretty trivial, but in an RV it is something to consider. This is one area where the RV specific range has an advantage.

The 4 burner stove top uses a trivial amount of 120V AC for the spark ignition, but the burners can also be manually lighted if there is no electricity available. The RV style range uses a piezo-electric spark generator that works from the mechanical twisting of a knob. My experience with those mechanical spark systems on BBQ’s is that they die rather quickly. I consider the lighting of the stove top mostly a triviality as I lived with a manual lighted stove for many years and never felt like I was missing anything.

My only other concern is that the 2 burner grates just sit there (2 grates over 4 burners). They are not held down or otherwise prevented from rattling around. The RV style range has silicone rubber grommets to hold the single piece grate. This is less of an issue for me than it would be for most RV applications since I can’t hear what’s going on in the back of the truck when I am driving up front. On the other hand I don’t want the grates bouncing around, chipping up the stove, or landing on the floor. I think it will be simple enough to place a bead of silicone under and around the grates to lightly wedge them in. I can use my standard trick with plastic wrap as a release barrier to avoid gluing them down permanently.

If anyone wants a brand new, never been used, RV style drop in range, I know where one is available really cheap…

To be continued…

[Ran D. St. Clair]

I love Angle Brackets

I just spent most of a couple of days making about 260 angle brackets. That’s about 23 feet of 2” x 2” x 1/8” thick aluminum L channel converted to 1” L brackets with two holes on each side. Why so many you ask? And so begins my theory of cabinets.

Most RV’s are made pretty much the same as your standard home kitchen. Cabinets are purchased pre-made, and installed. They are a little pricey, but considering all the work that goes into making them, it is more than worth it. Also, they come nicely pre-finished in a variety of attractive styles, with various doors and hinges to meet most any need. It’s a very practical approach, and one I recommend, but of course I am not doing that.

Your typical cabinet is a box. Lower cabinets typically have an open top for installation of a countertop, and they probably have a raised floor, which implies a couple of inches of lost storage. They also have a front face, which looks nice, stiffens the side walls, and provides a place to mount the doors, but restricts access somewhat. Inner shelves are somewhat optional, and they often have a system of pegs and holes, or even a steel track, for mounting shelves at different levels. Depending on the shelf mounting system the shelves can be somewhat loose to rattle around, or they can be wedged pretty tight.

Upper cabinets are similar. Some designs are flush on the bottom, but many have a top panel that is inset and inch or so below the top of the frame. They are designed to mount on the walls, but in most houses the ceilings are high enough to leave a gap between the cabinet top and ceiling. This gap is often filled in as a matter of visual design, or it can be left open and is sometimes used as a top shelf for rarely used items.

When the cabinets are bolted together the adjacent walls are doubled, representing a loss of space, but it is generally worth it for the modular design and simple installation. Sometimes it’s a bit of a problem when the room isn’t square, but filler panels and moldings can cover a lot of sins.

In my case, the entire inside of the living quarters is already a carefully constructed box of ½” plywood. There is no need for a cabinet back as the wall will serve.

Cabinet verticals are just ¾” or in some cases 1” plywood from floor to ceiling. It’s more of a book shelf concept than a cabinet, though the countertops and at least some of the shelves are full standard depth (or more). The verticals are somewhat sculpted, meaning they don’t necessarily go from floor to ceiling in a straight line. They are pulled back to open up the sight lines and reduce the sense of enclosure. This integrated top to bottom structure is much stronger and well suited to pounding I expect the back of the truck will endure. Each vertical is tied to the floor, ceiling and back wall with angle brackets, typically 6 of them for a full height vertical wall.

The countertops, and shelves are simply inserted between the verticals, and mounted with more angle brackets, typically 4 each for a larger shelf, and as few as 3 for a small or narrow shelf.

The brackets are almost always under the shelves or countertops where they are hidden from the normal angle of view. Some will be visible beneath higher shelves, though I expect that they will rarely be noticed. Each bracket is mounted with two #10 self tapping screws per side, 4 each per bracket. The idea is that every shelf is permanently mounted but easily remounted to suit different requirements.

There is no face frame on these cabinets. The plywood end grain may be covered for a smooth appearance, but it is not intended to be structural. The openings are therefore completely unrestricted to maximize storage space.

In a home application I might be tempted to forgo cabinet doors altogether. It seems I am always leaving them open, and they just block my access to what is inside. I realize that most people consider them a requirement just to reduce the visual clutter. In an RV they also serve the important function of keeping the contents in the cabinet as you bounce down the road.

I plan to have doors for all but the smallest shelves, which will have a substantial lip, 1” or more, to help keep the contents in place. I will also be using the soft rubber shelf liners to try to reduce the pounding. Some additional bungees, Velcro, wedge bars, or whatever may be needed depending on the specific items.

Deeper shelves, not entire cabinets, will have doors, but they will be hinged on the bottom and open like the tailgate of a truck. They will close with strong magnetic latches on each side to keep the contents in place. They will not attempt to cover the entire opening to the shelf above but will typically be about 8” high and leave at least a 1” gap to the next higher shelf. There will be no need for handles as the top of the door will be its own handle. The doors will be plain flat ½” plywood because I like a simple style and because it’s cheap and easy to make.

I realize that this design will allow some visual clutter to show, but it will also allow me some visual access to the contents without opening the doors. When a door of this sort is open full access to the interior space is available.

Counter tops will have neither a lip nor doors, though they may have a slight bull nose to help keep things from falling off. This strategy works fine when they are level, but I fully expect my truck will not be level much of the time. The implication is that I won’t be leaving loose items on the countertops. It’s just as well since countertop space is extremely limited and it is best that it not be cluttered with loose items. The microwave and other small appliances will be hung from the shelf above whenever possible.

I will have lots of shelves. Every spare bit of wall space will have an appropriate shelf. The entire space above and behind the toilet, for example will be filled with shelves, which is why I need so many brackets. One downside to this plan is that there is very little open wall space. I am even thinking to cover the front of the refrigerator and freezer doors with a mirror so I can have something close to a full length mirror. Who knows, it might even be a good diet aid.

Floor cabinets generally have a toe kick to reduce the strain on your back when working over a countertop. With open shelves all the way to floor, and the floor being the bottom shelf there is plenty of toe kick room, however I don’t want things on the bottom shelf (floor) sliding out and getting underfoot. Therefore I will be installing a vertical toe kick (or base board, or bottom shelf lip) to keep things where they belong. Obviously it will be inset from the edge of the countertops like any toe kick.

Normally kitchen cabinets are installed before laying the final floor, in my case standard vinyl flooring. Since the floor is also the bottom shelf of my cabinets, I will be reversing that order. The floor will be laid while the box is empty and all the cabinets built on top of it. One advantage is that there will be no convoluted shapes to deal with while laying the floor. There should also be no seams anywhere. Replacing the floor would be a pain, so I will be sure to select a very durable flooring material with a pattern that I can live with. Fortunately, if it lasts 10 years then it probably won’t matter, at least not to me.
Countertops are 37” high for use while standing, and desk tops are 29” high for use while sitting. Either way they are really just shelves. I haven’t decided on the countertop material yet. I am fine with Formica, but the typical particle board construction is heavy and may not be well suited to take the pounding. I may just laminate my own on plywood, or I may consider something like Corean.

I will be making and installing a few drawers, just below the countertop or desktop. These will all be shallow as are often useful for silverware, cooking tools, or office supplies. They won’t be fancy, just an open top box with a front face and a handle. They will sit on a shelf just below the countertop, constrained with short verticals on either side, and will all be longer than they are wide to minimize any tendency to wedge and jam. I don’t see any need for fancy rolling tracks for relatively small and light drawers. A couple of strong magnet latches on either side should keep them closed.

Cabinet finish will be very simple. Pretty much everything will be white latex interior semi gloss. I may consider water based polyurethane for extra durability, though repainting with latex is cheap and easy.

You may think that all that white will be boring, but I have my reasons. I dislike dark colors in enclosed spaces like cabinets. They just suck up the light and make it hard to see. Since my entire truck is an enclosed space, with no windows, and the only source of natural light is via the ceiling exhaust fan opening, I want that light to bounce around as much as possible. I am also paying for light with electricity and gasoline, so I don’t want to waste it. If I feel the need to add some color there are lots of easy ways to do it besides paint. It may not be honey walnut with burl accents, but I grew up poor and latex suits me just fine.

The overall visual effect should be simple, linear, and Spartan. I don’t expect that many others would particularly like it, especially the female sort. A part of me considers that a bonus. Fortunately, I have only one person to answer to and that’s the way I like it.

To be continued…

[geofkaye]

...I just buy the door fronts and make the box part out of 3/4 inch plywood using glue and air nails...I quit messing with kitchen cabinets a long time ago in moving vehicles.....they only last about a year or so if one is careful-if not they fall apart in a month on the road with all the vibrations and twisting of the box....there is no way around the coach movement or the movement of things inside the cabinets....overheads are more dangerous-specially over the bed...I stay away from doing that unless it becomes a big isssue and then overbuilding is the only way I'll do it....geofkaye

[Doc Weaver]

Originally posted by geofkaye:
overheads are more dangerous-specially over the bed...I stay away from doing that unless it becomes a big isssue and then overbuilding is the only way I'll do it....geofkaye

I built so many extra braces for my overhead cabinets, that they can be easily be seen. I would rather have safety than pretty.

Doc

[Ran D. St. Clair]

Wi-Fi Cables

I have been really struggling with my Wi-Fi antenna system, mostly the cables leading down from the antenna. I may be an electronics engineer, but I am not really an RF (Radio Frequency) engineer so I am making lots of mistakes along the way.

You may recall that I am using an Omni and a Yagi antenna combined with a splitter. The real difficulty is with the cables. The whole thing is mechanically based on a Weingard TV antenna mast system that allows me to manually raise and point the antennas, and also lay them down flat for travel.

My original thought was to bring down two separate antenna wires and use a switch in the living quarters to select between them. I then decided for various logistical reasons to mount both antennas on the same mast. That allowed me to place the splitter (combiner) on the antenna mast outside and then run a single cable through the roof.

The basic trade off with antenna cable (Co-Ax) is between flexibility and low loss. Large diameter stiff cables can have low loss, and therefore run relatively long distances, but they don’t bend very well. Even if they can be bent to a reasonably small radius, they are not intended to be bent and straightened and bent and straightened etc. Small diameter cables can be very flexible, but they are also very high loss, so you don’t want to run them very far. Not all cable types are meant to be outdoors in the weather either.

For example, I started off assuming that I would use LMR-400 cable as recommended by the web site that I was using, http://www.radiolabs.com/index.php. LMR 400 is good cable, so it’s not Radiolabs fault that it won’t work for me. It would be perfect if you wanted to put a Wi-Fi antenna up on your roof and just leave it there. It’s 0.405” OD and looses 6.6db per 100 ft at 2.4Ghz. I am still using 2 each 2 ft. LMR 400 cables from my two antennas down to the splitter (combiner). That chunk of cable doesn’t need to bend and the 3% power loss is negligible.

The cable from the splitter (combiner) that goes down through the roof of my living quarters does need to bend, and repeatedly so. At first I was thinking to use LMR 100, which is very thin and flexible. It is 0.11” OD but it looses 15.8db per 100 ft. at 450Mhz. It isn’t even rated at 2.4Ghz, where presumably the rate of loss is even higher. Despite this, LMR 100 is often used for very short Wi-Fi cables like 1 ft. or less from a laptop module to a clip on antenna. I am planning to place the transmitter/receiver module just under the base of the antenna, so the cable only needs to go a couple of feet, but LMR 100 isn’t recommended for outdoor use.

Connectors are another issue to consider. The connector at the transmitter/receiver module end of the cable is an SMA type, which means it has an outer ferrule of about 0.315” OD, with an internal thread and a central socket. The RP-SMA connector on the transmitter/receiver module has a matching external thread and a center pin. This sort of small threaded connector is often used for small laptop type modules with short little antennas that plug directly into the module. There are many other small and medium size RF connectors and I am not qualified to tell you about all of them.

The connectors most often used for large outdoor Wi-Fi antennas are type-N, with a type-N Female at the antenna and a type-N male on the mating cable connector. A type-N female is a large, robust, industry standard connector with external threads and a center socket. The type N Male has an outer ferrule with internal threads and a center pin. The OD on the outer ferrule is about ¾”, so you would need a rather large hole in the roof to feed one of those through. In my case the splitter (combiner) also has type-N female connectors.

I eventually settled on LMR 240 Ultra as the cable of choice for the two feet of cable that has to flex and enter through the ceiling of my living space. It is 0.24” OD with a Polyethylene jacket that is suitable for outdoor use. The inner conductor is stranded (not solid) which is why it is “ultra” flexible. It is rated at 12.7 db loss per 100 ft. at 2.4Ghz, which means I will loose just under 6% of my signal strength in 2 ft.

There are probably stores or web sites out there that will make this specific cable to order, but I will just be making it myself. I do not recommend this unless you have good soldering skills, and the proper equipment. The SMA connector requires a special crimping tool and also requires that you solder a very small pin. The type N connector is much larger and easier to solder but is still not trivial.

You can easily buy the necessary connectors from on line sources such as DigiKey http://www.digikey.com/, but you need to be very careful to use cables that are made for the specific cable type that you are using, otherwise the pieces just won’t fit. Another source that I have used to buy the LMR 240 Ultra (among other things) is http://www.universal-radio.com/.

Yes, RF cables can get very complicated. Actually, it’s much more complicated than I can explain here. Suffice it to say that it is much more like plumbing that wiring. Also, be warned, Wi-Fi uses 50 ohm cable, while broadcast TV uses 75 ohm cable. If you don’t know what that means, and not many people do, then don’t worry about it, but just don’t mix the two. If you do, then it probably won’t blow anything up, but it won’t work properly either.

I promised to tell you about all of my mistakes so here it is… I have thus far managed to waste about $75 on cables I can’t use. Learning can be expensive.

Beyond cables, I have many other concerns about my Wi-Fi design. Combining the signal from two antennas can produce unexpected results if you aren’t careful. If the two antennas receive the same signal out of phase with one another then they can cancel each other out. What I am hoping to achieve is to be able to receive a pretty strong signal from any direction, and a really strong signal in the direction that the Yagi antenna is pointed. That means my Omni and Yagi antenna need to add their signals together in that direction, not subtract. At 2.4Ghz the wavelength is only about 5” so the relative position of the two antennas is critical to a ½” or so. I understand the theory (at some level) and I won’t try to explain it here, but I have no way to know for sure if I have achieved my goal. A real RF engineer would need an anechoic chamber and other expensive equipment to know for sure, so I will just have to hope for the best.

I also have concerns about the long term durability of this setup. I will seal up all the connections with “Coax Seal” which is a tape like, tar like, sticky material commonly used to try and keep moisture out. It’s a harsh environment though, and I have 5 separate type N connections, two antennas, and a splitter all exposed to the weather.

There is also the issue of lightning strikes. Normally an antenna system would use a lighting protector, which is a device in line with the antenna cable which attempts to short the unwanted energy to ground. There is no really good ground on the truck though. It sits on 4 rubber tires and its not like I can drive a big copper grounding rod down to the water table and then run a big heavy wire to the lightning protector.

On the other hand, serious lightning involves millions of volts traveling hundreds or thousands of feet through the air, so those insulating rubber tires are like next to nothing. I think a lightning protector might provide some protection from static electricity but a direct strike could easily blow a hole straight through my roof. Fortunately we don’t get many serious lightning storms here in the San Francisco bay area, though I do expect that I might end up in Texas or the Midwest from time to time.

Beyond all the RF and antenna issues it remains to be seen just how accessible Wi-Fi hotspots will be on the road. Clearly I am putting a lot of time and energy into making this work. It is important part of my plans. The truth is, I still have a lot to learn though.

To be continued…