As things progress in life, new technology comes out that should be making our lives easier and more comfortable than what it was. Cell phones have gone from needing a back pack to the modern mini computer wonder we all use and take for granted. TV's have become "smart", vehicles use less and less fuel, and this list goes on.
For us RV'ers, the newest and hottest item to come out is the 12vdc compressor fridge. These units have made things so much better for RV's. They have no open flames like the conventional 2-way RV fridge, so they are safe everywhere for travel. They have much larger storage capacity in the same space, and they can run perfectly fine on un-even ground!! What's not to love about these things??
Enter the Boon-dockers. Those of us that love to really get away from it all by disappearing into the wilderness far from civilization(water/power/internet) are now faced with this new tech. Sounds amazing right? Well, not so much. One of the things with these fridges that make them great, also makes them a challenge for off the grid(OTG) campers. They are strictly 12vdc. Your battery only has so much power and then your fridge stops. When the fridge stops, the ice creams not so icy anymore.
Well, how long do these things run before we have issues?? If you are at a dealership you are going to get all sorts of answers, all of them wrong. It's not that these dealers are doing it on purpose, but that they are taking information given to them by the manufacturer's of these fridges as gospel. And we all know that no one would "extend" the truth just to sell something, right?!
Unfortunately the manufacturer's are grossly misrepresenting this product. One data sheet I saw claimed a 17 day runtime using 1 battery and a 100w solar panel! The caveat was that the solar panel had to be located in a certain part of North America, with the optimum angle, perfect clear skies, and during the summer solstice when the sun is at it's highest. Oh, don't open the fridge to use it either... Let's step into the real world and see how these things will actually perform for us OTG folks.
After looking at various brands of fridges and getting the data from them, and watching a few videos where owners have done load testing, it's apparent that the average power consumption of one of these fridges is around 1000wH(watt/hour) per day. This number doesn't seem too bad until you put this into context of what your RV is capable of. Using a standard battery bank setup of two 12v group 27 lead acid batteries, you will have about 1200wH of capacity in those batteries*. A standard 100w solar panel, in direct sunshine, will generate 500w of power a day( I am being very generous here). So what does all of this mean??
Knowing that the fridge draws 1000wh, if we were to just use our batteries, this fridge would run for 1.2 days(28 hours) before the batteries would be at the recommended maximum safe depth of discharge before starting to harm your batteries. I'm pretty confident that no dealership understands this, and I can guarantee that they won't brag about your food staying cold for just over a day.
Adding a 100w solar panel into the mix will buy us some extra time, not much, but some. Being generous, we will say that the solar panel will give us 500w per day of power(direct sun) just so we can keep the math simple. Over the course of that day the fridge would get 500w of power from the panel, and drain 500w out of the battery. Not too shabby!! We can now go 56 hours before our batteries are waving the white flag.
Let's double our solar panels to 200w. These guys will generate the same amount of power per day as the fridge takes, so we are not touching the battery now!! It's a draw and our batteries are just along for the ride.
Now 300w of solar panels are giving us a little breathing room and actually lets us use things like the water, heat and lights!! The fridge is taken care of and now we can actually start to put a charge back into the batteries. Its not a huge amount of charge, but 500w is still half of the battery capacity, which is much better than nothing!!
Now the optimum set up for an OTG RV is 400w of solar power. You haven't gone crazy with a massive amount of panels, but there is good power being generated. The fridge has all the power it needs and the panels are generating enough power to charge the batteries to full every day!!
What does all of this mean to the OTG crowd?? While the 12v fridge offers amazing benefits over the conventional 2 way fridge, it comes at the expense of needing a lot of power to work. My own RV is set up with 3600wH of lithium batteries and 400w of solar panels set up for ground use(not on my roof). In theory I should never have an issue with needing power, but in the real world, the sun doesn't shine all the time. When you take into consideration everything else that we use in the RV(water pump/furnace/lights/etc), you can pretty much cut your runtime and power generation in half for these fridges. Having a proper expectation of how long you could run your RV before you would have to connect a generator or find shore power is very important. For myself, I would not be comfortable using a 12v fridge with my current battery supply. I would like to have double the amount to guarantee that I would never have that fridge shut off on me.
Are these 12v fridges to be avoided? Absolutely not. They are such a great addition to the RV scene, and for a vast majority of RV'ers they will work just fine. If you are always staying at RV parks with power, or always run a genny to power your RV, you won't have any issue with these shutting down on you. If you love to camp like we do, you want the peace, tranquility and quiet that nature brings. The drone of a generator tends to get tiresome awfully quick.
In short, if you are going to run one of these and are an OTG warrior, be prepared to up your battery and solar game. A fridge full of ruined food quickly puts a damper on your camping trip.
Everyone stay safe, have fun, and keep making those great memories!!! Winter is all but over now so videos for youtube will start up shortly. I hope to provide the small missing gaps of information to everyone in hopes of making your RV experience just that much better.
*most group 27 batteries have around 100aH of capacity, so using 2 of them in parallel you would get 200aH, but for proper usage and life you can only use 50% of that. Any more and you will start to damage the battery and dramatically shorten its life!!