by McDave » Tue Feb 14, 2017 11:30 am
Hey Tommy,
I have a Norcold unit. I really like it. Model # DE-251E It is 12v and 120v only, no lp. However, there are advantages and disadvantages to each type. This 2-way AC/DC frig. uses a compressor and Freon, like your standard home unit or air cond.
3-way reefers work through the "absorption" system, which uses boiling ammonia vapors to absorb and remove heat.
When a 3-way is used on 12v or 120v, the voltage is sent to heaters to boil the ammonia. Also, 3-ways ALWAYS need 12v available to open the LP solenoid valve. You will also notice there is no "freezer" area in that unit. 3-ways MUST be vented to the outside.
My 2-way unit has a 40 watt compressor or to put it another way 3.3 amps at 12v or 0.33 amps at 120v when running. No outside vent required. She runs for 1/10 or 1min on, 10min off. So, at 12v consumption = 3.3a per hr /10 or .33amps per hr consumed. At 120v, .33a per hr/10= .033 amps consumed. At .33a, (12v) that is 8amp hrs/24hr day. A 100 amp deep cycle will power this unit for 6 days before reaching 50% discharge. It also has a freezer and makes ice, keeps ice cream and other frozen goods frozen.
You will notice the amperage difference at 120v. 3-way = 1.4a.... 2-way = .33a.... That's a 4 to 1 difference. This is due to the fact that the most inefficient way to produce heat (required to boil ammonia) is via electricity. 2-way Compressors are pumps, heat pumps that pump the heat outside the fridg. Also, 3-way cannot use lp when in transit.
I got this unit off E-bay for 170.00 shipped and it was brand new, taken out of a boat. I'm only giving you these numbers as a reference. It won't be long before an engineer pipes in to discount this info, but then again, engineer's fly paper airplanes. Pilots, ... well you know the rest...
McDave