Long trips by car often become a real test for lovers of quality food. It helps to keep food fresh away from civilization car refrigerator, which you don’t have to buy, but assemble yourself. This solution allows you to save a significant amount and get a device with the parameters you need.
A homemade unit often surpasses factory-made analogues in volume and cooling efficiency, if you select the right components. The design is based on the operating principle of compression systems, where the refrigerant circulates in a closed circuit. It is important for the car enthusiast to understand that modification requires not only technical skills, but also strict adherence to safety measures.
The main difficulty lies in adapting household equipment to the vehicle’s on-board network. Standard models operate on 220 volts, while the car only provides 12 volts DC. Solving this problem requires installing a special converter or replacing the engine with a compatible analogue.
Selecting a base for conversion: donor and its condition
The first step is to find a suitable housing. The ideal donor is an old domestic refrigerator small volume, for example, the Saratov or Biryusa models. They have thick walls and high-quality insulation, which is critical for maintaining cold.
You should not take units with a damaged circuit or obvious traces of rust on the evaporator. If the tightness system is broken, it is almost impossible to restore it in a garage without special equipment. It is better to choose a model that simply stopped turning on due to a burnt-out motor.
It is important to evaluate the internal volume and condition of the shelves. For road trips, it is more convenient when the internal space is as free as possible. Freezer compartment in this case it will be more of a hindrance, since it takes up useful space and increases energy consumption.
There is an alternative option - assembling a thermal container from scratch, but this requires complex calculations of thermal insulation. Using a ready-made body of an old refrigerator greatly simplifies the task and guarantees factory-quality thermal insulation.
Adaptation of the compressor to the on-board network
The most difficult technical point is starting the compressor from a car battery. The standard motor requires 220 volts AC. Direct connection to a 12 volt network is impossible and will lead to instant failure of the equipment.
To solve this problem, a device is used that converts the battery's direct current into alternating current. The inverter power must be at least 1.5 times higher than the compressor power to compensate for starting currents, which can be very high. inverter - a device that converts the battery's direct current into alternating current. The inverter power must be at least 1.5 times the compressor power to compensate for starting currents, which can be very high.
Why are starting currents important?
At the moment of starting, the electric motor consumes a current that is 5-7 times higher than the rated current. If the inverter cannot withstand this load, it will go into protection or burn out without starting the compressor.
There is a second, more professional way - replacing the standard motor with a motor running on 12 volts. Such compressors are often removed from faulty car air conditioners or purchased separately. This avoids the use of a bulky inverter and reduces energy losses.
When using an inverter, you must be aware of the load on the car's generator. Constant operation of a powerful consumer can lead to battery discharge if the car engine is idling. It is recommended to check the belt tension and battery condition before installing the equipment.
☑️ Checking the electrical part
Thermal insulation system and sealing
The efficiency of a homemade refrigerator directly depends on the quality of the thermal insulation. Even if you use a ready-made casing, over time the insulation could cake or lose its properties. Additional insulation will never be superfluous.
Sheets penoplex or extruded polystyrene foamare perfect for modernization. These materials have minimal thermal conductivity and do not absorb moisture. They can be used to glue the inner walls, having first removed the factory lining, if possible.
⚠️ Attention: When working with polystyrene foam and polyurethane foam, use a respirator. Vapors of chemicals in a confined space of a car can cause poisoning or an allergic reaction.
Pay special attention to the door. It is through this that the main loss of cold occurs. The rubber seal should fit snugly around the entire perimeter. You can install additional magnets or mechanical latches to increase the pressure.
The gaps between the insulation layers must be filled with polyurethane foam. This will create a monolithic layer that prevents air circulation inside the walls. However, it is worth remembering that when foam expands, it can deform the thin plastic of the inner chamber.
Installation and fastening in the car interior
Placing the refrigerator in a car requires careful planning. The device must be securely fixed so that during sudden braking or turning the heavy box does not move and damage the interior or passengers.
The best place for installation is the trunk or the space behind the rear seats. It is important to provide access to the compressor for ventilation. Condenser (black grille at the back) must be blown with air, otherwise the cooling efficiency will drop sharply.
| Parameter | Recommended value | Critical value |
|---|---|---|
| Internal temperature | +2...+5 °C | Above +8 °C |
| Network voltage | 13.5 - 14.5 V | Below 11.5 B |
| Current consumption | 4 - 6 A | More than 10 A |
| Operating time | 30% cycle | 100% cycle |
For fastening, use straps with a ratcheting mechanism or build a wooden box frame into which the refrigerator will fit tightly. It is advisable to lay vibration-isolating material between the device body and the car body to dampen vibrations of the running engine.
Energy consumption and autonomy
The issue of energy efficiency is acute, especially if you plan to spend the night in a car without a running engine. A standard household refrigerator consumes quite a lot of energy for automotive scales.
The average compressor consumption is about 100-150 watts during operation. Taking into account the inverter and losses, the current from the battery can reach 10-12 amperes. With a battery capacity of 60 ampere-hours, complete discharge will occur after 5-6 hours of continuous operation.
To increase autonomy, you need to:
- 🔋 Install an additional deep-cycle battery.
- ☀️ Connect a solar panel for recharging during the day time.
- ❄️ Set the thermostat to a wider temperature range.
- 📉 Use LED backlighting instead of incandescent lamps inside.
Installing thermal relay or the controller allows you to set the on and off temperature. For example, when it reaches +3 degrees, the compressor will turn off and turn on only when it heats up to +6. This significantly saves battery charge.
⚠️ Attention: Do not allow the car's starting battery to be deeply discharged. Leave enough capacity to start the engine, otherwise you risk being left without transport and far from help.
Maintenance and safety
A homemade device requires regular monitoring. Vibrations on the road contribute to loosening of contacts and fastenings. Periodically check the tightness of the bolts on the compressor and the integrity of the electrical wires.
Pay special attention to the refrigerant system. If you notice oily spots around the tubes or connections, it means a leak has occurred. It is impossible to operate such a unit - it is not only ineffective, but also dangerous to health.
When left idle for a long time, the refrigerator must be open to prevent mold from forming inside. It is better to lock the door in the slightly open position. Before each trip, check the operation of the thermostat and the absence of extraneous noise.
Remember that the refrigerant in older models can be a fire hazard or toxic. Avoid mechanical damage to the tubes. If you smell gas, immediately ventilate the interior and turn off the engine.
Is it possible to use a household refrigerator in winter?
Using a household refrigerator in winter is possible, but there are nuances. The oil in the compressor thickens in cold weather, making it difficult to start. In addition, the thermostat may not turn on the compressor if the temperature in the cabin is below the set temperature. For winter operation, insulation of the housing and, possibly, heating of the compressor crankcase is required.
How long does the refrigerator keep cold without power?
The time it keeps cold depends on the quality of the insulation and the volume of food. A well-insulated homemade box with a volume of 50 liters can keep the temperature below +10 degrees for about 10-12 hours without turning on the compressor, if it has previously been well frozen.
Do you need to register the alteration with the traffic police?
Formally, installing additional equipment in the trunk does not require registration unless changes are made to the body design (for example, cutting holes for fastening). However, if the refrigerator takes up seat space or blocks the view, inspectors may have questions.
Which inverter to choose for the refrigerator?
Choose an inverter with a pure sine wave output. Models with a modified sine wave may cause the compressor to hum and overheat. The power of the inverter should be at least 2-3 times higher than the rated power of the refrigerator to compensate for starting currents.
Why does the refrigerator make more noise in the car?
The increase in noise is associated with the resonance of the car body and the transmission of vibrations through the mounting points. The use of rubber gaskets under the legs and damping materials between the body and frame of the car helps reduce noise levels.