Replacing 3-way fridge with 12v

Don't compare the dometic absorption fridge on 12v to the Danfoss/Secop units. You'll never want to use the Dometic on 12v except while actively towing so you have your alternator charging.

5-6 A is about right for the Danfoss compressors during operation. That is a lot. If it ran at 100% duty cycle that would be about 140 amphours a day. You would need about 300 amphours of battery at 12v and around 400 watts of solar just for the fridge. That's roughly what I put on the med fridge boxes in Africa and Central America.


In RV use it's not going to run at 100% duty cycle but even at 50% it will still need a big upgrade in your solar electric system (around 200 watts and 150 amphours) or a couple hours of generator recharge time daily. Presumably you are already using your existing power system for other loads, so it's not available to run the fridge.

How much your fridge consumes is up to you. Think of your Rv fridge as a temperature maintainer rather than a cooler downer. Don't put warm stuff in itand keep the door sealed as much as possible. If you do that then the existing Dometic will probably work fine for you, as it does for most of us. The difference between it and the Danfoss based ones is that the Dometic will just get warm if you over use it, the Danfoss will consume all your electrical energy trying to keep up.
Personally I prefer the former failure mode to the latter.

What I and many others do is ice down a high quality cooler and fill it with already cold drinks when resupplying. That way the fridge only has food in it and gets much less load on it. Works well for us.

StephenH, the free piston stirling cooler is a great technology and you are lucky to have one. They are capable of achieving much lower temps than vapor compression coolers I think the reason they didn't take off us because they are expensive and at normal fridge/freezer temps the Danfoss compressors have more or less the same coefficient of performance so there is no real efficiency advantage. Now if you wanted to transport some Pfizer Covid vaccine your fridge would be the way to go.

The FPSC was originally for pharmaceutical transport (no biohazards). It is refrigerator only and is set to cool to 4 degrees C +/- a couple of tenths. It cools down quickly and once at temperature, does not take a lot of power to maintain. It can cool down warm items at the cost of more electrical use, but it also maintains the temps even when the outside temp is in the 90's F. It wouldn't be suitable for Pfizer vaccine, but I have seen freezer models. I was fortunate to find it at my local ReStore for what I consider a very reasonable $100. I should have picked up two when I had the chance.

I do believe it is the abbreviation of "free piston stirling cooler".

Ours has an Envirocooler label on it, but it is the same as this one: