I think everyone can take Richards posts for fact because he's a pro and everything he writes matches what I learned the hard way !!
We started off with a Glacier Bay system with holding plates and a huge 12V motor
driving that beast. It took 70A for the first 20 minutes or so, quickly draining batteries. Every two weeks (or more) I needed to put the gauge set on to check it, top it off etc. Every year or so the compressor
shaft-seals started leaking and a rebuild
was needed. I carried 2 compressors and one was out for repair most of the time. It was hell.
We now have Frigoboat. I think all units that use the Danfoss compressors work alike and have equal performance. I also see that most evaporators look alike and guess they have more or less equal performance. The differences are in the condenser like keel-cooler vs fan vs water-pump. I think we are lucky with our keel-coolers as we have 3 units in continuous use for 4 years now with no maintenance
except defrosting the evaporators every year or so. I read info on bad keel-coolers and hope they started making them better.
Now, a step away from scientific approach: we bought 50 pounds of beef tenderloin in Venezuela
, vacuum packed it all and put it in our freezer
. Our freezer
switches on at -12 C and off at -14 C. Six months later, the tenderloin was as good as the day we bought it, without freezer-burn (I think the vacuum packing helps). With our old system we couldn't do that because it would brake down every couple of months with all contents getting spoiled before we could repair it. The new system runs for a total of 20 minutes each hour on lowest speed setting. Volume is just under 5 cubic feet, largest flat evaporator (Frigoboat), air and water
temp 25-30 C in the Caribbean