How To Make Your Own DIY Camper Refrigerator To Save Tons Of Energy – Part 2

So how do you actually construct your own DIY refrigerator?

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.

Typical chest freezer. (If you want a chest *refrigerator*, they’re hard to find. But you could MAKE one!

<< Read Part 1 – This is Part 2

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.
If you can find a chest freezer to convert — or buy one 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.

English: Embraco type FGT 80HA compressor made...

Refrigerator compressor unit. (Photo credit: Wikipedia)

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.) But 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.

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 the $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!

DIY RV Air Conditioning (Works Wonders In Dry Climates)

A misting fan

A misting fan (Photo credit: Wikipedia)

What if I told you that you don’t need to use a traditional air conditioner in the desert. (Crazy right? But under certain circumstances, totally true!)

For an RVer one of the most expensive drains on your reserve battery power is running the AC. And if you live in a hot climate, it might seem ridiculous to consider living without it.

If you live in a hot and HUMID climate you may be stuck with using expensive traditional air conditioning. (At least for a little while longer, until technology catches up.)

But if you happen to live in a hot and DRY climate, you can often get away with something that may be far cheaper.

The one essential ingredient to make this type of non-AC cooling system work is something that most of us have in such ready supply that we don’t even think about it: WATER.

Ironically, that’s the one thing that runs in short supply in HOT and DRY climates like the popular Desert Southwest snowbird destination.

But if you happen to have a full water tank or — much better — are close to a ready water source, then you can have the makings of a quick and dirty evaporative cooling system.

If you’re not from the American Southwest, you may not be familiar with the concept of “swamp coolers“. These are what residents of hot dry climates use to cool their houses cheaply, without the use of air conditioning. Essentially a swamp cooler — technically an “evaporative cooler” is nothing more than fan that blows hot dry air through a water soaked fabric mesh. As the hot air passes through the mesh, some of the water evaporates into water vapor, carrying some of the heat with it, up and out of the building. In a dry climate, a swamp cooler has the benefit of not only cooling the air, but adding some desirable moisture to the parched air as well.

(If you’re from the humid Southeast, you might be wondering why the heck you’d want to add moisture to the air! Trust me. If you ever visit Arizona you will figure it out within the first 24 hours, when you wonder why you’re so dehydrated.)

A typical home air conditioning unit.

A typical home air conditioning unit. (Photo credit: Wikipedia)

A traditional air conditioner uses so much energy because it’s doing something that’s very difficult. It works on a heat pump principle, that uses some laws of how liquids and gasses behave at different pressures to force little bits of heat to go from a cold place to a hot place. A heat pump is always working “up hill,” and the steeper the temperature difference between the cold and hot place (think of your freezer) the more it has to work.

But an evaporative cooler only requires a simple and efficient DC fan, and sometimes not even that.

For illustration:

  • A great way to cool down your motorhome on the hottest and driest of days is to soak some towels and lay them onto the roof. If it’s really hot and dry, it may take a few buckets of water, but it’ll give you some quick relief from the “oven” effect.
  • To cool the inside, simply use a fan and a wet cloth. For a quick blast of cool air, lay a soaked towel over a fan.
  • For a semi-permanent “mini-installation”, hang a wet washcloth over your incoming air vent (with the fan on obviously) and spray it with water when it gets dry.
  • If you’re handy, you can turn this into a full swamp cooler installation by using a more efficient wicking mesh, a small water basin, and a small water pump.

A key thing is to make sure the air on the intake side is the dry outside air, so that it can absorb the water vapor. Once the inside air is saturated, you’ve hit your cooling limit.

Keeping the inside air dry enough to keep cooling it is where advanced air conditioning technology is required. There have been a lot of small developments in swamp coolers technology over the years, but getting past this hurdle has been a tough challenge for cooling engineers. (Check out the Coolerado system.)

But these ideas should be enough to get you started experimenting with evaporative cooling tricks. In future articles I’ll be discussing different plans for more sophisticated DIY camper cooling systems.


About the author:

“Boondocking vagabond” Mobile Rik is converting his Toyota Tacoma into a DIY RV Truck Camper stripped of unnecessary “modern conveniences” and outfitted with sustainable hacks for desert camping, including electricity-free refrigeration, waste composting, and ample sun-powered cookery and computing. Stay tuned for the full article!