So how do you actually construct your own ultra-efficient DIY RV refrigerator?
In many ways, you’ll find — at least conceptually — it not that hard. There are just a few key components you’ll need to tweak.
One area that most commercial refrigerators skimp on is insulation. But by combining the top-loading ice-box style design with ice-box class insulation — (i.e. 3″ of styrofoam) — you can have a design that allows very little heat to leak in compared to a standard refrigerator.
<< Read Part 1 – This is Part 2
Efficient Fridge Construction
Besides the insulated box, the only other significant components are the cooling mechanism, the thermostat, and any standby power that runs 24 hours a day (which in RV propane refrigerators would be the pilot light). All of these can be hacked and improved.
For a homemade refrigerator, you can move the compressor-condenser unit to a more ventilated area so it can dump the heat away from the refrigerator.
To save even more power on an AC-powered fridge, you can also install a modified circuit that puts the thermostat in front of the power switch, so that it only turns on when more cooling is needed. You may be surprised that this isn’t currently the case, but it’s because repeatedly “cold starting” the compressor wears it out faster. But with the redesigned efficient fridge, you may find as others have that it rarely turns on at all.
The famous DIY refrigerator design by Tom Chalko, who converted a chest freezer into a refrigerator (PDF) used only 0.1 kWh/day (less than 1/10th of today’s most efficient front opening refrigerators), turns on for only about 9 minutes a day!
A similar idea can be applied to automatically turn off the pilot light on a propane fridge.
Putting It Together
If you can find a chest freezer to convert — or just buy a Solar Powered Chest Freezer or Chest Refrigerator from Sundanzer — that may be easiest in terms of work. But if you’d like to customize the size and everything yourself, you can simply make a container out of wood or even a large cooler, insulate the heck out of it, and install the electronics and cooling system, which you can salvage from another small refrigerator. The only things that need to go inside the fridge are the temperature probe and metal evaporator unit, while the rest can go somewhere out of the way. Thinking about it that way, it’s really not that hard at all!
Heck, as long as you’re going the Do It Yourself route, here are some other questions for those up to the challenge:
- A refrigerator works by pumping out hot air into the environment as “waste.” Can you recycle that waste into something useful, like hot water?
- In most climates it gets much colder at night. Can you think of a creative way to use the normal day/night cycle to make your fridge even more efficient?
- Can you make a more efficient passive (evaporative) camp cooler that reaches lower temperatures and uses less water?
And in the meantime until your project is complete, there are tons of ways to improve the efficiency of your current refrigerator, which I won’t list, because you can easily find them all over the web.
Here are a few ideas for campers (and off-the-grid survivalists, for that matter) that aren’t usually listed :
- Can you alter your dietary needs to require less refrigeration? Besides cooking only what you can eat right away, think about healthy fruits and veggies that need less cooling, dried foods like what’s in trail mix, pickled foods, and even vacuum-packed versions of your favorites. (It’s almost like a healthy-eater’s bonus.)
- To prevent unnecessary fridge-door opening, what if you place everything you’ll need for the day into a cooler? If you do this at night before you go to bed and place the cooler in the coldest part of your camper, you can take advantage of free passive cooling. (Note: You probably shouldn’t attempt to store your frozen goods in a cooler for too long on a hot day.)
- A weird trick to keep your cold freezer air from dumping out when you open it might be to put up a baffle — even a simple piece of cardboard or better yet, a piece of plexiglas — inside the freezer. Just add a hole big enough to reach in and pull out what you need.
- The same idea can be applied to your refrigerator, but it’s probably more tricky, because of the shelves. Instead, you could follow this guy’s clever $2 idea and hang plastic sheets like the ones in the grocery store warehouse.
Hopefully I’ve provided enough inspiration for some of you to make a go at finally plugging up that huge leak in your daily battery budget, whether that means you’ll get another few hours of TV or another few days of boondocking! Even if you have solar panels, the energy savings from a more efficient refrigeration system could potentially mean that you won’t need an expensive solar upgrade to keep the lights on an extra hour. And the neighbors will certainly appreciate it when you don’t have to run the generator… possibly ever again. Now that’s huge.
Handy Tip: For any of you attempting a chest freezer to refrigerator conversion, or simply want an external thermostat to bypass standby power, the model that’s commonly mentioned is this $60 one from Johnson Controls.
Mobile Rik is converting his Toyota Tacoma into a DIY Truck Camper outfitted with a completely passive evaporative cooling fridge with electricity-free zeolite icebox. A conventional AC-powered system is embedded (unplugged) as an emergency backup. Stay tuned for the full article!