I’ve seen various sources that claim that modern home house-current refrigerators - including the mini-fridges and dorm fridges that might better fit a sub-RV size vehicle - are typically about an order of magnitude (sometimes more, sometimes less) more efficient electrically (in kWH / day) than 12V RV refrigerators.
But that sounds completely nonsensical. If it were true - why wouldn’t RVers just use an inverter?
Obviously, for non-electric-campground use, the outback dual or tri-power ones, that can run on propane make sense. But for the rest?
And is the efficiency difference true of the small minority of 12V fridges that use compressors instead of something else?
Hi, so I’m by no means an expert on this subject, but I can tell you that a retired engineer friend of mine who full times in an older diesel pusher chooses to use a small high efficiency dorm size fridge instead of the larger dometic 3-way fridge that came with the coach. I think he has a 3K inverter and around 500 watts of panels on his roof, with a robust bank of AGM batteries. He believes it is about twice as efficient, especially since, like me, he doesn’t buy much that needs kept cold. For myself, the vanlife style experience means space is even more prescious and so I use a small portable 12 volt cooler and find that’s all I need (but I also very seldom stay anywhere that gets hotter than 75 to 80 degrees).
There are several factors that contribute to efficiency in your energy system. RV fridges, as you mentioned, are generally powered by a 12V compressor and sustained through propane to keep your fridge cold. Residential fridges are powered by A/C current and require far more continuous wattage.
To answer your question would require to compare data specs side by side per model. But generally speaking, residential fridges require much more energy to keep cold than RV fridges - less efficient for your energy system.
Generally speaking, yes that’s true. However, the poster asked about the smaller dorm size mini fridges specifically. I recommend comparing the specs of a high efficiency mini fridge with a comparably sized Dometic or Norcold RV fridge, keeping in mind that the mini fridge compressor only cycles on intermittently through the day. An electrical engineer friend of mine chose the mini dorm size fridge because it ultimately pulls less power from his system. Note that you can buy high efficiency RV fridges too, but they are four to six times the price for comparable size. If doing a true cost benefit analysis comparison, the unit’s prices should of course also be a factor.