Quote Originally Posted by RV Sailor View Post
John thanks for the explaination. I already understood everything after sentence 1. Not confused about ah vs amp. Nit confused how to convert amps to watts either

A commercial refrigerator has a heating element is something I didn’t know. Do they all operate that way? Are they all such energy hogs? When an appliance says 1000 watts does that mean it draws 1000 watts all the time it’s on.

I understand my 12 volt reefer on our 35 ft sailboat. Everything there I convert into a and ah. There is an average of 3-4 amps used which cycles intermittently depending on how hard the compressor has to work to keep the reefer at 38 degrees.
It uses anywhere from 45 - 70 amps per day from our batteries depending on outside temps. There is no heating element

Is what you are saying it would be more efficient to put a 12 volt only reefer in instead of these 110 units ( disregarding the conversion of inverting the loss
of converting 12 v to 110.)
Absorption refrigerators have traditionally been used in RVs, and they use a heat source to boil ammonia. There is no compressor in these units. Generally RV units are two-way (LP or 120VAC), or three-way (LP, 120VAC or 12VDC). Both versions require 12VDC to power the control system and sometimes fans even when they are operating with other heat sources. There are even versions that burn diesel or kerosene, but I’ve never seen them in an RV. The three-way units are not nearly as common as they used to be, primarily because the 12V mode didn’t do much cooling.

So the 12V control circuit draws a steady 2A, and then the heater power used varies by the environmental conditions.

There are also 12V compressor refrigerators on the market now which reduce power consumption some.

Most RVers operate on LP while AC power isn’t available.