120vAC fridges and freezers can certainly be made to work on batteyr power, but often the 'savings' is just not there.
An inverter with a Low idle current or dedicated feature to nearly eliminate parasitic draw when compressor is not running, will eat up a lot of the 'savings'
Rigging and wiring up the other accoutrements to make it function as intended, will eat up a lot of other savings. The 120Vac chest style freezers are only more efficient due to the extra insulation. Increase the insulation to 4 inches on Any fridge box and the efficiency will go way up.
Yes the 500$+ price of a 12v compressor fridge is a hard pill to swallow, but so is trying to amke a 120VAc unit work reliably, without the likely necessary doubling in battery and recharging capacity to run it.
Among 12v fridges, there is not huge differnences in energy consumption. No one 12v fridge is Vastly superior than another in the energy consumption world if all the variables are equal. Such claims are ludicrous.
The biggest differences come in the insulation of fridge box and door/lid seal, and how well the condenser is ventilated. Meaning do not block the cooling vents, or ask it to work in a 130 degree vehicle baking in the sun comparing its consumption to one in the 60 degree ambient shade.
I had a sawafuij compressor powered norcold with passive condenser, which I found Noisy and annoying. I did make sure the condenser was well ventilated. When the fridge failed at the 5 year mark and I replaced it with a danfoss powered Vitrifrigo, the design of the VF allowed me to better ventilate condenser. Both had/have the same amount of extra insulation, the Norcold had better door seals, but the door twisted with age and did not seal as well as it should have.
The VF uses about 10 to 15% less battery power than the Norcold, to keep colder internal temps, in my Van, with my installation/ventilation methods.
This is not a blanket statement that DAnfoss powered fridges are more efficient than Sawafuiji or Waeco powered 12v compressor fridges, but my opinion definitely leans heavily toward danfoss/secop based 12v compressors based on my personal experience with the units I own(ed). The danfoss compressor controller also allows easy addition of 12v computer fans(0.5 amps max) that cycles on and off with compressor to help suck out hot air, or push ambient air through condenser, rather than relying on passive ventilation or convection.
Also, while the Sawafuji compressor has the potential to be much louder, there is a lot of variability in how loud any specific unit will be, and much depends on the vibration suppression efforts employed by the manufacturer/ assembler, and the temperature of those vibration suppression bushings.
I expended a lot of effort in dampening noise and vibration my Norcold with success, but an empty fridge or a heavly loaded fridge could negate those efforts and cause angry fists to make dents in fridge door when Awoken by harmonics caused by the swing compressor.
Those efforts, as well as angry fists, might also have contributed to its demise from loss of refrigerant. and those 3 weeks of going back to a cooler and block ice while waiting on the funds and delivery of VF fridge, still cause nightmares.
12v refrigeration and more than enought solar power for it, makes Van dwelling from a chore into a luxury, in my opinion. Definitely the best upgrade I have done. Bite the bullett and well ventilate the cooling unit of whatever fridge you choose to employ.
If you do go down the inverter/120vac unit rabbit hole, you still have to makes sure its compressor and condenser are not bathed in hot air it has removed from the box. So many people never consider that the heat pulled from the interior of any Fridge, has to be expunged to the exterior, and the more efficiently this is accomplished, the less energy consumed, and the degree of that difference can be vast.
Those in stick and bricks usually never consider its electrical consumption and do not care as the fridge alone might only consume 17 cents worth of grid power every 24 hours, but a hot vehicle baking in the sun relying on battery power certainly needs to.
Some friends of mine in a stick and brick bought a larger fridge which would barely fit into the opening in their kitchen, and complained it was not cold enough. My IR thermometer found the drywall behind the fridge at 135F after I slid the fridge out and was assaulted by heat. I modified cabinet above fridge to allow heat to escape, but did not lower thermostat and the next morning things inside the fridge portion were frozen.
Look into Truckfridge for low cost danfoss powered fridges and there is a recent thread on MaxBurton fridges which are even cheaper.
