DAY ONE, FORMING THE IDEA: Been thinking about coolers: including rotomolded coolers, 12vdc/120vac vehicle specific coolers, and even dorm fridge/freezers, that would fit into my trailer's "galley", without re-doing everything. But, for cheap, as is usually my preference. I've looked everywhere for used equipment that would be the right price, and right size, to take the place of an Igloo Cube 48 quart cooler, that nests inside the galley. It was a perfect fit for the spot, so that's why I chose it, in 2013. I use it for my perishable foods, and never open it 'til preparing meals, so everything stays cold. I used two other coolers for drinks (a 50 qt. Coleman Extreme, and a small Igloo Maxcold). None keep cold for a full 3-day trip, unless in very cool weather, but the Cube fares worst, even usually kept unopened and shaded, always.
I've tried every trick, including using frozen bottles of water in all, to supplement the ice, but have decided that nothing is up to the task, at least in this climate. So, I hunted for a replacement for the CUBE, but found none cheap enough for my limited/no budget (with 6 coolers sitting in a shed, unused, my wife would not like to see me spend $250-400 for one cooler, or substitute. However, I can drink cool, not cold, drinks from the other coolers, but really need to keep perishables (meat, cheese, "egg beaters", and ketchup, mayo, and mustard) fresh, for three or more days. I always have my Spam, and other canned food, in my pantry box, but sometimes I like variety.
I decided to try a last resort, before getting a small 1.1 cubic foot freezer, to use with parkpower, just for the perishables, for $100-150. It might not work where I would put it, because it might add too much heat into the galley area, where I also have stored white gas, and gasoline (in the generator and it's external tank). I'm going to keep using the 48 qt. cube cooler, but I'll put a smaller cube cooler inside it, with rigid foam + Great Stuff + foil duct tape filling the gaps between the large and small "cubes".
I'll have room inside the large cube to put 2" of rigid foam under the small one, and 2" on top (glued to the bottom of the large lid; both coolers will keep their lids on). I can force in 1.5" all around the sides (I'll use 2" foam, carved to fit the contours of the small cube (thus both coolers will keep all their insulation intact, and the rigid foam will supplement that). Lastly, any gaps that I can't fill will the rigid foam, will be filled in with Great Stuff spray foam. Foil tape will cover any exposed foam.
Since I already have both "cubes" (my wife no longer uses the small one), and both are in perfect condition, I should be assured of having at least one small, cold, cooler after the completion of the experiment. I'll be using two pre-frozen ice packs, at -2 degrees F. (guaranteed to last 60% longer than ice -we'll see-); they will leave me 400 cubic inches of cool, dry, storage, for a few luxury perishables. Or I can always survive on Spam and beans....
DAY TWO, PSYCHING MYSELF FOR THE BUILD: I tried another form of insulation, before, trying to achieve the same goal: a cold cooler. I've tried wrapping my Coleman Extreme cooler in an insulated "cozy", made of Ultratouch, of chopped denim, faced with reflective Mylar, back in 2014. I tested it by packing the cooler, wrapping it in the "cozy" (totally sealed in; squeezed into the "cozy"), and sitting on top of another layer of insulation on a table , in the shade of my canopy (it was sealed in before I even left home).
On my last trip, in cooler weather, I used 64 lbs of ice (8x8 lb bags), initially distributed this way: my 50 qt. Coleman Extreme had 24 lbs over 12-14? 1-liter bottles of frozen iced-tea, the smaller Igloo Maxcold had 12 lbs over 3 frozen qts. and 8 20 oz. unfrozen water bottles, and the 48 qt. Cube had 16 lbs over 10? frozen iced-tea bottles and two 2.5-lb packs of Earl Campbell's link sausage (my favorite) + 2 (frozen) ice packs on the bottom. All this was loaded up into truck & trailer about 11 pm, the night before.
In the morning, prior to leaving, I shook down the coolers to settle the ice level, and added the remaining 12 lbs of ice (stored in the freezer, overnight) on top of all three. Then I left for camp (@10 am).
One semi-warm and two cool days later, with three cool nights between, I inspected the remnant of my ice left in the three coolers into the Extreme, before breaking camp. The Maxcold (in my truck floor) had very little ice, 90% water, but the water bottles were very cold, so I left it as it was. The Extreme, sitting in my truck bed, had 20% ice left, and three iced tea bottles left in it were half-frozen. The Cube fared worse, with the ice-packs now liquid, and no free ice in the cooler, and the four previously frozen iced-tea bottles left were liquid, also. The remaining sausage package was moved to the Extreme, still with ice. The water was cold, though. Everything was much colder than on my usual trip, due to the cool ambient temperatures that weekend (no A/C required, hooded sweatshirt at night). I will now always freeze my prepared drinks, in advance, as they keep better than using ice alone, and convert the Cube to a "perishable food-only" storage unit, so it remains sealed 99% of the time.
I might just buy a small freezer, just to use for my preparations at home, freezing the tea/water bottles in advance, to be ready to pack for camp at anytime. My wife didn't like me cramming her freezers with the tea bottles for several days, as I prepped for this past trip.
As for the insulation of the Cube: it has walls of less than an inch, with probably only 1/2" of insulation. That's why they are not very efficient, but I chose the 48 qt. Cube just for its' shape, able to fit it into the space I made for it (battery started out in that space, later a fuel jug, and the Cube last). I hadn't had ice problems before I started to camp in my TTT (I drag raced, and fished a little, overnighting in the truck), because my prior trips were usually two days or less, and with ice replacements readily at hand. But when camping, I like to set up, and chill out for a coupla days, not going to a store to get more ice. I just wish my coolers would chill out, too.
supercooler continued, day two addendum (self questioning)
Why not build an insulated box from plywood and foam, to meet similar specs of the rotomolded coolers? Not much space left there; just enough to reach in over the Cube to turn the galley lights on, and there's electrical to the left and (unseen) behind it. There's also an angle aluminum rail to the left and behind it, to restrict movement, and the shelf support post to the right. That's why I want to try to use the shape (Cube) I have, instead of starting from scratch. Besides that, both Cubes have lids that fit securely, hinged on the back, and with little "catches" molded inside. I would have trouble duplicating that, with hardware, on a plywood box. And, the 1.5-2" insulation I'll add, will completely surround the inner Cube, so the dual shells and dual inner liners shouldn't hurt, so I'll leave them intact. Another thing, if I were to try to build a plywood box, it would end up overweight, overbuilt, and with too much hardware...sorta like my trailer.
DAY THREE, THE PROJECT STARTS & FINISHES?:I started the insulation install for the cube into cube experiment. I bought some 2'x2' squares of pink foam "project boards", along with a roll of Reflectix foil tape (I find it to be easier to use than the Nashua foil tape that I sealed my A/C ducting with), and Great Stuff spray foam (against my better judgement).Since the foam board material was only 1" thick, I knew I would be unable to completely fill the 1.5" area uniformly surrounding the inner cube, so tape and spray foam would be be needed.
I cut two pieces to put under the inner cube, and one to place in between the closed lids. A test fit showed me that I would need a strap to hold the outer lid firmly closed, so I retrieved a spare ratchet strap to do the job (this cooler assembly is only going to be opened a few times at camp, since it is for perishable food only).
Then, I cut four 12"x12" squares for the inner sides, slightly trimming the edge of one for a forced fit, and 5/16" off the tops, to match the top of the closed inner cube. I taped the four sides to each other, and to the bottom piece, and proceeded to fill in the gaps with the GS.
As is my usual luck with spray foam, I couldn't control the applicator, getting too much overfill, spreading over the edges of the closed inner cube. Trying to wipe off the excess, I just spread it more, and to me, as well. I hate Great Stuff, but what's an alternative?
I'm waiting for it to set, and dry, and I think that I'll be able to remove some excess from the inner liner (it doesn't adhere too strongly to smooth plastic). After that, I'll tape up the exposed foam, for a better look, and better seal, and take pictures of the Frankencooler I'm creating.
HOURS LATER: Cube in a cube cooler completed. I cleaned away the excess Great Stuff foam (it wasn't difficult to remove from either type of "cube" plastic), and used the remainder of the foil tape roll (30 ft?) to seal all the foam. I had just enough left to tape the edges of the removable inner foam lid.
It turned out better than I thought it would, since previous encounters with Great Stuff (and pink, rigid, foam) hadn't turned out well, before. Metal and wood are my materials of choice, but foam was the material needed for this project.
I'm freezing the two ice packs overnight, and will conduct a test Sunday-Tuesday, to see if the improved? cooler will do the job. I'll put a temperature gauge inside it, and see what it says at the test conclusion.
P.S. I just realized that I was forgetting a crucial component that the high-performance rotomolded coolers ALL have, a rubber gasket or sealing ring around the lid. I still feel that the cube coolers have a tighter "snap" closure than most regular coolers, but I should get a rubber sealing piece for the lid(s), to give the Franken-cooler a fair chance in competing with the modern supercoolers. I may still have some (low-profile) self-adhesive rubber seals left from re-doing my hatch seals, a couple of years back. I'll check.
my supercooler build;partially OK (at best), needs pre-cooling and real ice to work
Three weeks+, and two 72-hour cooling tests later, I have no joy at the results. I ran the tests in an air-conditioned spot, at a constant 79-80 degrees, to best evaluate any modifications to the cooler(s). I first tested the coolers, just tightly strapped shut, then with an EPDM foam seal around and just below the overhanging lip of the lids, sealing them tighter when (ratchet) strapped shut. To my disappointment, the results were the same. Obviously the cube in a cube is working better than before, with the open lidded (temp gauge in the opening) test canteen of water (Stanley stainless single-wall, with 1 quart of water) retaining some cooling, while the "cold" ice-packs I used, failed to. I'll use real ice next trip (no more tests), pre-cooling the inner cube first, partially freezing (just to the point where ice crystals are forming in the items), and place ice over them (they'll be sealed in plastic bags). I'll see if using an additional foil-faced fiberglass square piece, placed between the two lids will help, but I hold no illusions about the outcome. Ice, ice, and more ice to come, until I get a rotomolded cooler, or an electric ARB, Engel, or the like.
