Deep into the planning stages of my build and 12volt refrigerators seems to be disgustingly overpriced. They are roughing 6-8x more of a equivalent size and functionality. I used my Kill-a-watt to audit the power draw for my full sized 120volt fridge and it used 5kwh in 72hours or 50% of my planned battery bank excluding power needed to run the inverter. My question is, are the 12volt units that much more efficient if I’m planning to have ample solar and DC-DC charging and I’ll be driving moving a fair amount. My goal is to have enough sources of power and large enough batteries to not have to worry about powering off my inverter and using as much power whenever I need it. Any thoughts would be appreciated!
Greetings & Welcome!
All of the electric fridge/freezers use a similar amount of power regardless of whether they’re running on AC or DC. The difference is the use of the inverter, because they draw extra power, whether in fact they’re actually in use or not. People get around this by using a temperature probe in the fridge or freezer, connected to a relay to only power on the inverter when it will actually be in use.
While I successfully went the above route in the past, I’m now using a 3-way fridge/freezer salvaged out of an RV for $50. It’s designed to run on propane, and requires no electricity in that mode. I mounted it using a gimbal like on a boat, so it stays level whether my rig is or not. I also modified it to be multi-fuel, since I don’t like propane, but that’s just my personal choice.
So I saved my marvelous fridge/freezer from the landfill, and it only cost me $50. That’s a win/win in my book. I only use the 12v option while driving, or the 120v option if I have shore power.
It’s far easier & cheaper to conserve the power used, than it is to produce more power.
I went the 12V Vitfrigo route. They use 60-70% of the energy the AC fridge will use, so you end up needing less battery, solar, etc. Plus, you can leave your inverter off most of the time. They were developed mostly for marine applications, so you don’t have to worry about it being level all of the time. The DC compressors are also more compact so they save space. Any system will work. Just your personal preferences. Do be aware that the 3 way (AC/DC/Propane) frigs are very inefficient when on 12v.