AC/DC Fridge vs DC only.

[boywonder]

Originally Posted by rean1mator

exactly how much of a delta is there between running it off ac vs dc?

If the use case is running an inverter to run the fridge on AC, let's assume that the inverter is 90% efficient and the fridge AC to DC converter is also 90% efficient. The total efficiency is .9X.9=.81 or 81% efficient, so you would be wasting almost 20% of your battery capacity as heat in the inverter and in the fridge power supply.

It's actually a bit more complex than this since a large inverter will waste more power than a smaller inverter if a smaller inverter can handle the load.

These efficiencies are total guesses but they may not be too far off........

[nwlady]

Does anybody know if a danfoss ac/dc fridge runs better .."colder in warm weather".. in AC mode than than in DC. I saw a comment that DC takes less energy. Is that between there is loss if using the AC mode... or less energy used because it is not cooling as well.
I am trying to decide between a danfoss AC/DC and danfoss DC. Looking at Truck refrig models and Vitrifrigo. thank you

[larrie]

I went DC. The AC/DC units have a converter to change the AC to the DC that runs the compressor. The converter comes in handy if you have a small battery bank and stay multiple days at places where there are hookups. If you mostly boondock then there is no need. Of course if the fridge is a portable unit then the AC side would be handy if you had it as a cooler in the garage.

[BUFFALO]

I don’t think it will run better. The compressor is dc. So it’s always running on 12 volt supply. The ac has to be converted to dc and there are losses there.
If you have an on board battery charger that is powered by shore power you don’t need the ac version.
It kind of depends on your equipment and use.
I have a small battery bank in my van and a dc tf130. Works well with no hookups. And when plugged in to shore power, the battery charger is keeping the batteries topped off and the fridge still runs on dc.
My ac/dc edgestar fridge lives in the kitchen at home and runs on ac non stop for cold drinks. Never used the ac function when it was in the van.
I’m not sure why you would run on ac.
I suppose maybe it gives your battery bank a rest and time to charge up properly while plugged in? Can someone who runs an ac fridge chime in?

[velo47]

We went with a DC only Isotherm because, well, it was cheaper. Since the compressor runs of DC power anyway, we couldn't think of any advantage to having the AC/DC version. It also seems more efficient to run straight off DC instead of AC converted to DC, but that's just a guess.

[Charliesmom]

Another DC only Isotherm CR130. Performs well. We mostly boondock. 360 AH LiFePO4 batteries with 350 watts of solar (230 roof; 120 suitcase).