I used a combination of board foam and spray canned foam (doesn't add that much weight) and Reflectix bubble-pack foam from Lowes. There are two kinds of spray-on foam, Closed-Cell and Open-Cell. Closed-Cell foam is high density, rigid foam when cured. Open-Cell foam is lightweight, flexible and carries the same properties as cellulose and fiberglass insulation when cured. The Dow Chemical Great Stuff Cracks and Gaps Foam Insulating Sealant is closed-cell, dense, rigid foam, paintable, sandable. The Dow Chemical Great Stuff Window & Door Insulating Foam Sealant is an open-cell, lightweight, foam. Both are moisture and air-migration resistant. Closed-Cell foam has twice the R-value of Open-Cell foam, which is why you need the Reflectix to add to the R-value seal it all in.
Reflectix alone has a really low R-value, something like R-4, when it is applied in contact with a surface, as would be the case in a van. It's like an R-15 when installed in an attic, stapled to the 2x6's that line the roof, so that it's got several inches between the roof and the insulation. But when used in a van in conjunction with polystyrene and canned foam, will add valuable R-values, and will become the primary moisture and air-migration barrier (as long as each and every seam is sealed with foil tape).
Polystyrene Foam board 1/2"
Canned Spray Foam (Windows and Door)
3M Spray Adhesive (77 and/or 90 - I used both for different functions and locations)
Loctite Power Grab All Purpose White Construction Adhesive (calking tube, so you'll need a calking gun)
Foil tape (the thin stuff, not the insulated stuff that you'd use on an HVAC air duct). Duck Brand, or, Reflectix now also makes foil tape for the Reflectix insulation.
Be sure to use a combination of board and canned foam to ensure that every possible void is completely filled. Be careful in the doors because of mechanical issues with the locks, obviously. Cut a board to fit a void, and then place it in the void, holding it in place by either spray adhesive or Loctite adhesive. Once in place, fill in the rest of the void with canned foam. Once the entire thing is insulated, cover it all with Reflectix, making sure to seal every seam. Leave no bare metal, or as little as possible. No point in wearing a heavy winter coat if you don't button it up, or in wearing fingerless winter gloves.
Allow about $600 and five days to properly insulate the thing. Any shortcuts and you'll pay dearly for it. If you're going to live in an iron box, you might as well make it livable.
"For the plywood for the floor is it better to go with hardwood plywood or standard plywood? Is 1/2" thick enough or is 3/4" better?"
Standard 1/2" (which will be something like 9/16 in reality) is fine. After installing it, make sure you give it 2-4 healthy coats of Minwax Polycrylic. Half an hour between coats, then let it dry overnight. Allows you to keep it clean, as oil spills won't immediately soak into the wood. Also, the combination of polyurethane and acrylic, as opposed to one or the other, gives the finish a hard surface that resists all but a nail sticking out of the bottom of a skid, but also gives it a unique property of being easy to slide stuff on when you want to slide it, but it "grabs" the skid and won't let it move around while driving. Clean and reapply a couple of coats every 6-12 months.
"Do you put plywood all the way back to the point of touching the doors when they close or do you leave a few inches at the back so the 8' extends far enough forward to take care of 2 skids?"
You want plywood deck wherever you have a skid. In my van, between the closed rear doors and the bunk, there is exactly 108 inches of plywood, since some of the automotive skids are oversize, and for the really odd skids that you run across now and then. The few inches at the back is where a forklift operator can do the most damage. Moot, I think, has a cross-wise length of E-Track at the very end of his van at the doors, and then has plywood from that point forward. It's an excellent idea, as the metal E-Track helps protect the wood decking, and also gives you another place to secure an E-Track strap. I don't have that, and I have had a couple of forklift operators actually stick the forks into the edge of the plywood, like sticking a fork into a biscuit to open it up for butter and jelly. Bondo, a power sander, and a fresh coat of Pylocrylic fixes it, but a row of E-Track would have prevented it.
"Do you secure it to the floor with screws? How do you know where not to put screws so you don't cut through an electric or fuel line?"
Yes, with self-tapping screws, about 2 inches long should do it. Take a quick survey under the van and look for fuel lines, fuel tanks, and electrical lines, then hope for the best. Most vans, when you put the screws along the outer edges of the plywood, you will not be screwing into anything that you shouldn't. But take a quick look underneath before you start juuuuust to make sure.
"Is it safe to have your hotel power batteries in the cargo area?"
Depends. If it's AGM or Gel batteries, absolutely safe. If it's sealed maintenance-free batteries, it's safe, but these can outgas if charged at too high a voltage. If they are regular batteries that will boil, spit and spill when charged, the kind that you have to regularly add water to, absolutely unsafe, as the outgassed hydrogen gas is just daring you to show it a spark.
"How large an inverter do you need if you are willing to unplug tv, pc and fridge when you want to microwave so it's an either/or and not all running at once?"
Depends on the power requirements of your microwave. If you have an 1800 watt microwave and a 1500 watt inverter, you can unplug stuff all day long and it still won't work. har, har, har. The power consumption of the microwave (or whatever you have that draws the most power) is the primary factor in determining the inverter size. When I first got one we were doing a lot of stuff out in the field with things like corded power circular saws, too far for an extension cord to reach, so I needed a 3000 watt inverter to handle the 2500 watt draw of some of the power tools. I no longer need one of that size. Check the microwave to see it's electrical wattage consumption. The wattage it consumes is different than the cooking wattage. It may say "1800 watts of cooking power", but it my be drawing 2200 watts from the electrical outlet. The metal label on the back of the microwave or inside the door will tell you the wattage. For compact microwaves, you can usually add about 500 watts to the cooking power (output power) to get the power consumption wattage. A full size microwave (1.6 to 2.2 cu ft) will generally draw at least 1800 watts and have 1250 watts of cooking power, a mid size (1.1 cu ft) will generally be 1500 watts and have 1000 watts of cooking power, and a compact microwave (.7 cu ft, room for a 10" dinner plate) will draw 1200-1400 watts and have 700-900 watts of cooking power.
One thing about microwaves, wattage draw is directly related to overall cooking times, and thus overall amp draw. The larger, higher wattage microwaves will draw a lot of power at once, but it will cook quickly. Lower wattage microwaves will draw much less power, but for a much longer cooking time, since the lower wattage causes them to take longer to cook. I have a small microwave that has 900 watts of cooking power. It draws 1200 watts of power from the electrical outlet. Directions on a package of frozen broccoli and cheese sauce may say cook for 4 minutes, but that assumes a full-power microwave. With mine, it takes more like 10 minutes. So, 1200 watts is 10 amps at 120 volts, and 100 amps at 12 volts. For 10 minutes that's about 17 amp hours drawn from the batteries. A full size microwave drawing 1800 watts of power is 15 amps at 120 volts, 150 amps at 12 volts, and for 4 minutes that's just 10 amp hours. So, the more power a microwave has, the faster it will cook and the less overall amps it will draw. The question is, can your batteries take such a significant power draw even for just a few minutes? A 150 amp draw is a serious amp draw. If they aren't specifically designed for high amp draws, the answer is no, so you may be better off with less power being drawn for a longer period of time. Not that a 100 amp draw is something to be dismissed. It's not, but at least a high quality hybrid battery can handle that easier than a 150 amp draw.
A full-power microwave will have a much higher amp draw, and will thus require batteries that have very thick plates. You need true solid lead plate deep cycle batteries to use a full-power microwave. Lower powered microwaves will have a lower amp draw, but for a longer time, so you can get away with using hybrid "marine" batteries to a degree.
"What brand is the best inverter? Are there any brands of batteries or inverters to avoid?"
Tricky question. The "best" inverter is something by Outback Power, but it'll cost you dearly. Next best is Xantrex. A Xantrex inverter will also cost you dearly, but it'll be pocket change compared to a high end Outback Power inverter. Forget I mentioned Outback Power. Xantrex is in the price range of most other pure sine wave inverters. Outback Power is not.
Pure sine wave is better than modified sine wave (otherwise known as pulse-width modulation, or PWM). Microwaves will cook quicker, motors will run cooler and quieter, everything runs more efficiently on pure sine wave. A clock on a microwave cannot keep anywhere close to accurate time with a modified sine wave inverter, since the clock uses the 60 Hertz pulses of real electricity to keep time, something that modified sine wave electrical current doesn't have.
I have a Cobra 1500 watt inverter that works well enough. I really should get that AIMS brand pure sine wave inverter repaired or replaced, though, since modified sine wave cannot be good for the fridge compressor, among other things. As for as POS brands of inverters, Cobra is a good one. Stay away from just about every other brand you can find at a truck stop. Trip-Lite is also a very good brand of inverter (I think Ray has those at Espar in Romulus), certainly far better than the Cobra, IMHO. AIMS is good (inverters2us.com), but I've had one go bad and I know someone else who has had two bad, but I know several others who have had no problems at all with them for years. I can highly recommend them, but just not without slight reservation.
