Refrigerators are one of the indispensable equipment in both caravans and motorhomes. Caravan lovers are among the many alternatives when choosing a refrigerator that does not take up space and that is as large as possible, with its cooling and ice-making capacity satisfactory.
The most popular model among the refrigerators designed for caravans, which are called three systems, are refrigerators that can operate both at 220 V mains voltage, 12 V voltage and LPG. However, although these cabinets are very useful, they are not preferred by everyone due to their high prices.
Using a 110 V AC refrigerant in a caravan
Although it seems to be the easiest alternative to use a 220 V refrigerator in the caravan via the inverter (electronic device that converts 12 V to 220 V), it requires the use of an inverter with a capacity of at least 50% more than the refrigerator power, since the refrigerators draw high inrush currents at the time of operation. In this case, the selection of the inverter to be used becomes important.
There are two types of inverters in the market, called full sine or modified sine, tailored to the needs of users. While the full sine inverters convert the 12 Vold DC voltage to the sinusoidal curve very close to the mains voltage characteristic with the help of electronic circuits, the modified sine inverters imitate the sine wave curve by offering an output voltage in the form of a square wave or a triangular wave.
Refrigerator motors are machines that work on electromagnetic induction principle. The induction, discovered by Michael Faraday, starts with a coil made of conductive material (like copper). … the direction of the magnetic field depends on the passage direction of the current; consequently, the alternating current passing through the coil will cause the magnetic field direction to change at the same speed as the alternating current frequency.
Which inverter should I choose ?
Positive and negative rises in the 110 V AC voltage obtained from a square wave voltage inverter will cause the magnetic field changes to be sudden and hard.
Therefore, it will cause the refrigerator motor to vibrate at the moment of rotation. Since this change in square wave will take place in one fifty per second (periot), even if we do not notice this hardness at the time of operation, inefficient operation of the refrigerator motor may cause unexpected malfunctions or lead to an early life.
However, when using a full sinus inverter that gives a sinusoidal curve, the rotational motion of the refrigerator motor will be smooth and vibration free, it will perform its task efficiently.
If a refrigerator suitable for 110 V AC voltage is used in the caravan, an inverter that produces a full sine curve with a capacity of at least 50% more than the refrigerator power should be used.
Idle losses of inverters
Inverters are generally machines operating at 90-95% efficiency. In other words, if the inverter is connected to the battery and running, the inverter will spend 5-10% of its power as a cooling and internal requirement even if no device is running.
For example, a full sinus inverter with a minimum power of 600 W, selected to meet the refrigerator and general needs, will consume about 30-60 W as an internal requirement. The lost energy of a 24-hour inverter will be 24×60 = 1440 W.
In the home environment, 1440W energy will run your oven for only 20 minutes, maybe not enough to cook a meal, or even if it is the energy you use in the shortest program of your washing machine; The exact equivalent of caravan life is to serve a thirsty lemonade to a thirsty person in the desert.
Which refrigerator should I choose?
Although three system refrigerators are the most useful refrigerators, we have mentioned that they are expensive, and suitable inverters to be selected to operate only 110 V AC powered mini-refrigerators have the energy disadvantage.
In this case, as a third alternative, refrigerators with compressors with DC motors, designed for 12 – 24 V DC operating voltage, which can operate without the need for an inverter, stand out as a different alternative.
The biggest advantage in choosing a refrigerator designed for 12-24 Volt DC operating voltage in the caravan is that there is no need for an inverter that will work continuously to operate the refrigerator, and inverter losses will be minimized.
In addition, for the 110 Volt AC devices to be used, the power of the inverter to be chosen will be smaller and a second saving will be achieved and a cheaper initial installation cost will be created.
Sparty Woodpecker recommends choosing a refrigerator suitable for 12 -24 V DC operating voltage and an inverter that will meet the minimum needs in order to use electrical energy efficiently in the trailer.