Hi guys.

Must agree with all the above. Gary certainly is right about efficiency. We have been freedom camping continuously for two years and noticed that we saved about 3 to 4 days gas per 9 kg bottle in our upright Dometic 2 door fridge and freezer with a defrost required every two - two and a half weeks in humid North Qld summer (about 18 days instead of 10 -15 ). Now in South Aus where the climate is cooler and not humid, and still haven't had to defrost after 3 weeks (still no build up!).

To digress a little, we also have self-installed a 12 volt upright 90 litre freezer which runs on our batteries 24/7 and has only had to be defrosted once in 6 months. It pulls only 3 to 4 amp/hr. Awesome. We haven't had to run our generator for 4 months now except to deliberately blow the cobwebs out. And no, we don't got to bed at 6.00 pm, more like 10 to 11 pm., with a light, laptop, tv running. Everything, including our twin tub, runs on our roof solar power except for the hot water and fridge. At daylight, our batteries have never been below 12.6 V for six months. Sorry to digress even further, but we have also busted the myth that solar power is better in North Oz, with our early morning daylight power being no less then 12.7 V in all kinds of weather over the last 5 weeks. 

Back on track, we consistently defrost as soon as the ice build up reaches 2 ml thickness, exactly as recommended in the fridge manual, and this has proven to run both the fridge/freezer and Engel freezer efficiently and more cost effectively without a doubt, as we have logged our gas/battery power useage for 2 years to develop the efficiency of our off the grid power resources. Another hint, which you are probably aware of, is that the metal ribs in the fridge compartment should only have frozen droplets on them, and not build up whatsoever, to indicate most efficient running.

Regards to you all, have a happy New Year,

Eddie