The choice of refrigerator for your off-road caravan is essentially a personal one that will be influenced by your previous experiences and the way in which you wish to operate at and away from conventional 240 volt power facilities.
Characteristics of 3-way absorption type fridges and 12 volt compressor type fridges which you may wish to factor into your decision. Some brands are “T” rated and will perform better in higher ambient conditions.
3-way Absorption Fridges
As the name implies, these fridges are designed to run on three alternative power sources – 240 volt mains, 12 volt DC battery (power supplied from the 4WD through the 7pin trailer plug) and LP gas.
The fridge will operate efficiently when connected to 240 volt mains and LP gas although as the ambient temperature rises above 36ºC performance starts to diminish when operating on the 12 volt supply.
Whilst travelling, the fridge is switched to 12 volt DC and runs from 12 volt battery via a direct connection to the battery system of the towing vehicle. Whilst connected to this 12 volt power source of the towing vehicle, the refrigerator can at best in high ambient temperatures maintain cabinet conditions. The fridge should only be connected to 12 volt DC whilst travelling as the battery will drain quickly if not being charged by the vehicle’s alternator. It’s recommended that if you are travelling and stop for a long lunch break, switching to gas will help boost the cooling.
It is important that the caravan is level to obtain optimum refrigeration performance.
12/24 Volt DC Compressor Fridges
These fridges run exclusively on 12/24 volts DC which means that the fridge runs at full efficiency at all times including travelling. Unlike the 3 way fridges the 12 volt power supply for compressor fridges comes from the caravan batteries (no hot wire is required from the trailer plug).
The 12 volt compressor fridges are dependent on a good 12 volt power source that necessitates an integral 12 volt battery system within the caravan. Importantly, consideration will have to be given as to what additional systems are in place to maintain correct battery charge. This presents no problem when there is a 240 volt power supply available such as found in caravan parks, as the caravan electrical system incorporates an automatic battery charger. Similarly whilst motoring, the towing vehicle’s electrical system can be modified to provide charge to the caravan battery system. However, in an unserviced location (bush camp) solar power will be required to maintain the correct battery/s charge.
When stationary without access to 240 volt power, the battery system will require supplementary charging. This could take the form of solar panels and also possibly a backup compact generator. Compact, lightweight, efficient generators that are extremely quiet in operation are readily available. The operation of such generators may be restricted by local rules and regulations of the area in which you are camped. Remember, if solar power is to be relied on then the solar panels need to be in sunlight, so camping under a shady tree is not an ideal situation.
Comparing the Two Types of Refrigerators.
- Whilst 3-way fridges are silent in operation, the 12 volt compressor fridge has a motor driven compressor which like your domestic refrigerator emits a ‘humming’ noise as the fridge intermittently cycles on and off. Some find this noise intrusive particularly at night.
- 3-way fridges are necessarily vented to the exterior of the caravan, and whilst sealed from the interior of the caravan, in extremely dusty conditions, certain components at the rear of the refrigerator can be subject to dust ingestion requiring periodic cleaning.
- In extremely hot ambient temperatures, compressor-type fridges are considered to be more efficient than 3-way fridges. To assist 3-way fridges to cope with extreme ambient temperatures, a supplementary fan can be fitted at the rear of the refrigerator cabinet.
- 3-way fridges require strict attention to leveling of the caravan. The compressor fridge will be more tolerant of slope, although for personal comfort, one should aim always to have the caravan sited as level as possible.
- Keeping the 12 volt power supply to the compressor type of fridges can at times prove difficult i.e. if the weather is poor and there is insufficient sunlight for the solar panels to charge the batteries.
- As a rough guide, vans with a 3-way fridge may require one 80+ watt solar panel to keep the batteries charged depending on location and usage. Vans with compressor fridges require two or three 135 watt solar panels to keep the batteries charged.