After 7 years of Experience with installing nearly 1,000 refrigerators in our Off Road Caravans and Camper Trailers, we have learnt what works well when camping. We have several types and styles of refrigerator in our test equipment: Engel, Waeco, Vitrofrigo and Autofridge products. We have experience with customers in the far north in difficult heat and conditions and have tested and measured the performance of many refrigerators.
Is there really such a thing as an “eco-friendly” fridge that is effective?
To be eco-friendly, the refrigerator has to run off renewable energy. This eliminates ALL 3 way refrigerators which principally use LPG. Three way refrigerators are also inefficient and take time to settle to maximum performance after travelling. They are “old technology” and frankly need to be banned!
Modern 12VDC refrigerators use an approved eco-friendly refrigerant and can operate comfortably of 12VDC power for short or long extended stays.
What are the requirements for an “energy efficient” refrigerator?
Chest type refrigerators are the most efficient in not losing the “cold” when opened. They can also be built with optimum insulation which is essential.
Insulation is very key and high quality insulation can be heavy unfortunately. The low quality “styro-foam” type is lightest and least effective.
The size and design of the condenser is a major secret to energy efficiency when the refrigerator is operating with high loads in particular.
There is a new type of “technology” that changes the compressor speed depending on the amount of power available to vary power consumption and store the energy in plates. Is this effective?
When there is power capacity available and the fridge increases compressor speed and cooling “power” it has to be able to transfer this increased power through the condenser plate to the outside environment. The majority of variable power systems cannot vary the capacity of the condenser plate. The resultant long term energy performance is only slightly improved and no where near the energy saving of an eutectic system.
What is eutectic technology?
Virtually every major boat has eutectic refrigeration as it is the best energy efficient AND performance effective refrigeration system in 12VDC. Eutectic fluid surrounds the four walls of the interior cabinet, acting as an 'ice bank', or cold storage compound, for the contents of the cabinet. Once the eutectic fridge has been pre-chilled, the eutectic system need only be run for a few hours per day on its maximum setting to maintain the desired temperature - even in ambient temperatures of 32 °C+.
While the eutectic fridge is running, the fluid is frozen and the cabinet contents are thoroughly chilled, which reduces the duty cycle time of the compressor and so reduces the power consumption over a 24 hour period.
What would be the energy performance difference between a eutectic refrigerator and a non-eutectic refrigerator?
Our experience is that the Autofridge eutectic refrigerator uses about 50-60% of the power needed compared to the other 60-80 litre refrigerators in our test equipment. The Autofridge uses a DANFOSS BD35 compressor which is the same as that in the vitrofrigo and Waeco products we have. (Figures quoted assume normal usage of your refrigerator, e.g. opening/shutting the lid to use or replace contents.)
A lot of 12V refrigerators have the compressor speed fixed at a low RPM to minimise power but this compromises performance in very hot conditions. We set the speed of our compressors (at the factory as a factory set option) to nearly the highest speed: 3,500 rpm. This gives excellent compressor performance. The eutectic refrigerator “cycles” on and off at a lower frequency and for less time which results in the energy saving. However, when the power is needed, the Autofridge has the capacity to produce maximum power.
What are the performance characteristics of Eutectic refrigerators?
Our experience is that the temperature is even and unbelievably consistent which is what most customers are looking for. The cabinet temperature is based on the thermostat setting. Because of the mass of eutectic fluid around the cabinet, items touching the cabinet wall are kept at a consistent temperature.
Can you have a Fridge/Freezer in Eutectic?
A camping tip with eutectic refrigerators like Autofridge is to place your frozen food and ice at the bottom of the refrigerator and place 2 layers or “bubble wrap” material on top of this. Then use the space above as a refrigerator. Tweak the thermostat to about the mid point and after a bit of practice you will get the 2 spaces in harmony. This is not ideal for long storage low temperature freezing but we have run this way with ice for the drinks and the frozen premium steak very comfortably over a 2 week period.
Can you have the Eutectic fridge operate as a Freezer only?
Definitely, and an excellent one at that. Just set the thermostat to coldest for excellent performance.
Whilst it may be more effective than those units that drive direct
What is the comparison with the new separate space Fridge and Freezers?
Some of the new units have dual compressors and their power consumption as a result is very high. Generally running a separate space for freezing to the refrigerator space is difficult to do in an energy efficient way. It is far more efficient to have a separate freezer to the refrigerator. This has an added advantage that if during the trip there is not a requirement for freezing (either a poor fishing trip or you ate it all!) then you can rest one of the units until needed later in the trip.
The Autofridge can be operated in any of the following ways:
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Complete with: 8 x 13W Super Thin Panels - 10A MPPT Controller - Flexible Lead for fitting to Pop Top Caravan