Electric cool box purchasing advice: how to choose the right product
- What you need to know
- Electric cool boxes come in three broad categories, which are defined by how they work: thermoelectric, absorption and compression.
- Unlike passive coolers, electric coolers can keep things cold as long as they have power.
- Most coolers come with a 12 volt connection for your car and a 100-127 volt (North America) or 230 volt (Europe and most other parts of the world) plug for home.
- Most electric coolers have a capacity of between 20 and 40 liquid quarts (20-40 L).
- Thermoelectric boxes can also keep things warm, usually up to 149 °F (65 °C).
Cooling off on hot summer days
In hot temperatures, there isn’t much better than a cold, refreshing drink. At home, in a café or at a beach bar, of course, this is no problem — there they have refrigerators. But if you’re camping or on a day trip, a cold beer can sometimes be hard to find. Simple passive coolers, i.e. well-insulated boxes cooled with ice or ice packs, can keep drinks cold for a while, but after a few hours they lose their effect. Re-freezing the cooling packs or getting fresh ice is inconvenient and often simply impossible outdoors. In these instances, electric coolers can come in real handy.
Electric coolers keep their contents cool as long as they are supplied with electricity or gas. When their power supply is interrupted, they work like passive coolers. This means that without power, they can still keep things cold for several hours. Electric coolers are not just for camping, they are suitable for anywhere you can power them.
The three electric cooler technologies
Coolers are either active or passive. Passive coolers require external cooling, such as a ice packs or ice. Active coolers, on the other hand, can cool the contents as long as they are supplied with energy. Electric coolers belong to the latter category. They can be split into three categories based on their design or the technology used. These are thermoelectric, absorption and compression coolers.
Thermoelectric coolers have an electrothermal converter, otherwise known as a Peltier element. This is why they are also often referred to as Peltier coolers. The Peltier element creates a temperature difference when current flows through it. Depending on which direction the current flows, the contents are cooled or heated. These coolers are equipped with two heat sinks, one inside and one outside the box. Under voltage, the heat is conducted from the inside to the outside, which is why it can get a little warmer right next to the box.
Although thermoelectric coolers are mainly used to keep things cool, most models can also keep things warm. If the current flows in the opposite direction, cold air is conducted from the inside to the outside and the contents remain warm. These coolers don’t have any moving parts that may wear out, which makes them quite durable. Cooling capacity depends on outside temperature. As a rule, these coolers can reach a temperature that is 64 to 86 °F (18 to 30 °C) below the ambient temperature outside. When it comes to keeping things warm, however, outside temperature does affect performance: thermoelectric versions can keep food and hot drinks warm at a maximum temperature of 140 to 150 °F (60 to 65 °C).
Compared to the other types, thermoelectric coolers are cheap and lightweight, which is why they are the most popular. These coolers can also be placed on their side – they don’t have to stand upright. Although they aren’t particularly loud, they do make a bit of noise. Last but not least, thermoelectric boxes have a high power consumption.
- Can be used in any position
- Heating function available
- Cooling capacity depends on outside temperature
- Moderate noise level
- High power consumption
Absorption coolers lower the temperature inside using coolant. In a closed circuit, the coolant is liquefied in the condenser. The refrigerant then evaporates in the coolant, extracting heat from the interior. In the absorption cooler, the gas returns to its original liquid aggregate state and the cycle begins again. No mechanics are used: the cycle is driven only by the heat generated by electricity or gas.
Absorption coolers can be both electricity and gas-powered. Similar to Peltier coolers, they can reach a maximum temperature of 86 °F (30 °C) below ambient temperature. Within this range, however, the temperature is often adjustable. The absence of mechanical components means they are easy to maintain, durable, and almost silent.
These units don’t have a heating function. They also have the highest power consumption of the three types. With gas, however, they are much more energy-efficient. Last but not least, they always need to be placed upright, otherwise they lose power.
- Almost noiseless
- Electricity or gas operation
- Long-lasting and low-maintenance
- Often adjustable temperature
- Energy-efficient with gas supply
- Cooling capacity depends on outside temperature
- High power consumption
- Horizontal installation necessary
- No heat function
Compressor coolers are similar to refrigerators in the way they work. Here, too, it is a closed circuit. The compressor compresses the gaseous refrigerant, causing it to heat up. It is then pumped through the condenser. There, the refrigerant releases heat into the environment, cools down and becomes liquid again. A metering or throttling device through which the now liquid refrigerant is forced lowers the pressure. The refrigerant enters the evaporator, where it is returned to its original gaseous state. In the process, heat is extracted from the interior and released into the environment. When the refrigerant arrives in the compressor again, the cycle repeats.
Unlike the other variants, the interior temperature of a compressor cooler is not dependent on outside temperature. As a rule, such boxes can maintain a constant temperature between -4 °F (-20 °C) and 14 °F (-10 °C) . Within this range, temperature is continuously adjustable. At outside temperatures of around 104 °F (40 °C), compressor coolers are the only type that can keep your food really cold. They are also the most powerful. Despite the high performance, they consume very little power.
However, this high performance also comes at a high price. The compression system makes the unit not only heavy, but also noisy. If you sleep lightly, you should either look for another cooler model or place the compressor cooler out of earshot. They cannot heat their contents.
- High output
- Interior temperature not dependent on outside temperature
- Adjustable temperature
- Can be used in any position
- Low power consumption
- No heating function
Additional purchase criteria
In addition to the type of cooling mechanism, energy supply and power consumption are extremely important factors that will influence your purchase. Capacity, ease of transport, and useful extras should also factor into your decision.
Energy supply: connection and consumption
Most coolers have more than one power connection. Most coolers come with a 12 volt connection for your car and a 100-127 volt (North America) or 230 volt (Europe and most other parts of the world) plug for home. Coolers are also often equipped with a 24-volt connection for a truck. If you have one, you can also connect your cooler box to a solar panel. However, make sure that the power of the solar panel is somewhat higher than that of the cooler so that you can supply the device with sufficient energy even when there is less sun. Some coolers can come with rechargeable batteries. Absorption coolers can also be supplied with gas via a cartridge with a suitable connection or adapter. The required pressure is usually 30 or 50 millibars (mbar).
The energy consumption of an electric cool box depends greatly on its design and capacity. A large thermoelectric cooler will consume significantly more power than a small compressor cooler or an absorption cooler with gas. Models with eco mode are great for saving energy. The connection also plays a role in power consumption. For example, a car battery does not supply as much energy as mains power.
For the same capacity, a thermoelectric cool box consumes about three times as much as a compressor cooler. Absorption coolers are best when powered by gas, as they are not particularly efficient with electricity. If you plan to use your car’s 12-volt connection for power, you should pre-cool the contents at home. The car battery may not provide enough power to cool down the box and its contents, let alone freeze them.
Manufacturing material and insulation for good insulation
Cool boxes are usually made of plastic. After all, they are designed for travelling, so too heavy a material would be a poor design choice. This said, you can get models made from aluminum. The metal is heavier, but much more robust than plastic.
To successfully insulate against cold and heat, most models use PU (polyurethane) foam. After it has hardened, it has very good insulating properties. It is dimensionally stable, light and water-resistant. Some models are equipped with a double wall. This means that even less cold escapes outside. These are usually compressor coolers.
Although the size of the boxes is relevant for transport, for the actual use, the cooler’s capacity is much more important. Often, capacity is specified in liquid quarts, which is roughly one liter (0.94 liter). Make sure you don’t confuse liquid quarts with dry or imperial quarts. You should be clear about how much space you need in your cooler before you buy it. If you have too little space, you will not be able to cool enough food. If you have too much space, the cooler will consume excess electricity unnecessarily. You can often get the same model in a range of different capacities. Common capacities are 20 to 40 quarts (20 to 40 L). A capacity less than 20 quarts (20 L) is a bit small, even for personal use. Although this does not sound like a small size at first, liquids, for example, aren’t stored loosely but in bottles. According to manufacturers, a 23 quart (22 L) cool box fits 32 cans of 11.1 oz (330 ml) cola, 16 bottles of 18.6 oz (550 ml) drinks, and 9 bottles of 25.3 oz (750 ml) red wine, which is probably an a bit of an optimistic calculation. On the other side of the spectrum, there are models with a capacity of 60, 80 or even 90 quarts, but they are bulky and heavy.
Weight, transport and comfort
Weight is another crucial factor. After all, you may have to carry or pull your cooler along hiking trails. Too much dead weight is impractical, especially when the box is full. The type of cool box plays a big role in the weight. A small 20-quart Peltier cooler usually weighs about 11 lbs (5 kg) empty. The situation is similar with absorption coolers, unless they are connected to a gas bottle, which adds a few pounds. Compressor coolers are the heaviest because of their internal mechanism. Compared to thermoelectric coolers, these often weigh twice as much or even more.
It is also important that your cool box is equipped with handles that ensure comfortable carrying. They are either on the lid, as is the case with many thermoelectric models, or on the sides. With lid handles, you should make sure that the lid is closed before you lift the box.
Some manufacturers go one step further in terms of transport comfort and equip their coolers with wheels. You can pull these models behind you like a suitcase. This allows you to transport more weight with less effort. In order to be able to pull these coolers while walking, they have a telescopic handle. Last but not least, some coolers come with shoulder straps.
Practical interior fittings
Some coolers have compartments or dividers inside so that you can store food and drinks separately. However, compartments like these are not ideal for coolers with a small capacity as they take up too much space. High-quality compressor coolers are equipped with LED lighting, just like a refrigerator: as soon as you open the lid, the light comes on. This means you can also use the cooler at night at the campsite without any problems.
Useful extra features
Depending on the model and price range, electric coolers come with useful extras. Some models come with a USB port where you can charge your mobile phone or other small devices. Other coolers can be controlled via an app. This allows you to set the temperature remotely, for example. The most important function, however, is the battery monitor. These will switch the cooler off before it draws too much power from your car battery, to prevent it from going flat.
Cleaning and safety tips
An electric cool box should be cleaned in the same way as a refrigerator. First, you need to disconnect the power supply. Then you need to empty the box. If necessary, remove components that can be disassembled and clean them separately. Clean the interior with a cloth or sponge and a bit of cleaning agent, before finally wiping it dry.
When transporting the unit in a car or truck, make sure that it is placed securely. If you plan on putting your cooler on a car seat, you should strap it in. Otherwise, you could be seriously injured in the event of an emergency stop or crash.
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