Oberneldon said:
In my Prius I lost the advantage of leaving the fridge on the floor of the class b where the temperature was always cooler than the ceiling. There is very little separation of temperature in the parked car.
Brent
That is an often overlooked factor, the heat within the vehicle. It affects not only the box temps from an insulation point of view, the hotter temperatures make it harder for the condenser to release this heat removed from the box to the atmosphere.
My van's ventilation has improved enough that I can keep the interior much cooler than in 2007 when I got the Norcold, Yes I expend electricity to run the fans, but then the fridge runs less often and for less time making up for that consumption, and then some.
When My VF was new, i was running it outside my cabinet during the day, while I modified cabinet to accept it as it is a smidge taller than the Norcold was. When I did the fan swap, replacing the 120mm sleeve bearing 72cfm 0.12amp fan mounted to pull air through condenser, with a Noctua NF-f12 (53cfm, 0.05amp) pushing air through condenser, the duty cycle dropped by an average 40 seconds, Instantly.
This seemed too extreme, to placebo like, and I thought perhaps The ambient temps had fallen, or some other factor was contributing to the lessened duty cycle, But six hours later I timed another compressor on and off cycle and it ran for 45 seconds less than before the fan Modification. And there was 0.07 amps less draw with the lesser amp draw fan, and there was much less noise with a quieter fan.
Seeing this improvement and deciding that it was not just placebo like expectation driven, I went a step further, making the cooling unit tunnel so that the fan could only suck cool air from the floor below the fridge, and push it once through condenser across compressor and controller, and out the louvered vent or into next cabinet compartment. Later on I added the air filter after dust build up became a concern.
I did not bother keeping duty cycle records past this point once I got it tucked tightly into cabinet. The fridge was so much quieter and seemingly more powerful and efficient than the Norcold I was just satisfied and life went on.
Really with door openings, their duration, changing ambient temperatures, warm foods placed within, how much any fridge is going to draw will vary quite widely. Manufacturer specs as to consumption over an hour or consumption when compressor is running vary so widely and are almost entirely meaningless compared to real world use with the tools to measure that consumption.
With the new Norcold in 2007, when running it in a 90 degree garage, I was afraid 130 watts of solar could not keep up with the fridge load, and I made the cabinet big enough to accommodate more insulation and allow proper ventilation over condenser, and when installed and having a battery monitor in place, I found that 130 watts was more than enough for the fridge, but not so for my other increasing electrical loads and in 2011 or so I added 68 more watts.
Really, my fridge concerns now are just its defrosting every so often. The Norcold would kind of self defrost if I put something warm into it, but the VF cold plate never does this unless I turn the thermostat to minimum.
I could improve the insulation in, on, and around the door for more improvements, but this is pretty low on the to do list. I'm not fighting to conserve each AH at this point. But on initial install I could not just slap it in the cabinet either. I wanted the insulation to be tight, and the ventilation optimized, and the compact cooling unit with forced air through condenser seemed such a better design than the Norcold's passive condenser.
The lower noise, higher cooling ability, higher efficiency, and ability for compressor speed adjustments and the ability for the controller to power more fans gives me the priceless warm and fuzzies.
Pre 2007 I used to spend a few cumulative months a year in Baja. Id get to my spot and park for 3 weeks. I'd have ice for 5 days. Nearest town was a 45 minute drive. I dreampt of being able to freeze fish I caught, a cold drink, all sorts of luxuries that a fridge allows.
In 2007 when i was researching fridges and decided against absorption, I knew I needed solar too. When I got the solar and the fridge installed, van dwelling just became so much better, and with an electrical surplus most of the time, the doors were opened wider.
Not having to empty a stinky cooler and go buy block ice every 5 days..... priceless.
The sticker shock of a 12v compresor fridge is real, But it pays for itself with time, and the convenience is priceless.
