When speaking of portable 12-volt powered refrigeration, the words "cooler" and "refrigerator" seem to be used synonymously when in fact they are quite different. So what are the differences between 12-volt coolers and 12-volt refrigerators, and which one is best for your needs?
12-Volt Refrigerators use the same type of refrigeration equipment as is found in standard home refrigerator freezers. A portable refrigerator is cooled using refrigerant gas, a refrigeration pump, a condenser and coils. The main difference is that the 12-volt refrigerators are built in such a way that they do not need to be perfectly level to operate properly. Another great difference is in power consumption. The refrigeration pump runs on very little power, and the insulation in the refrigerator door and walls are of high value.
All of the DC powered portable refrigerator freezers are thermostat controlled. Some have a dial thermostat control and others use a digital thermostat. The chest style 12-volt refrigerators and freezers by Engel and Summit Appliance are also capable of deep freezing, making them perfect for EMS and field researchers.
What is the typical lifespan of a 12 volt refrigerator? Generally we see refrigerators by Dometic Waeco, Summit Appliance and Engel working well even after five or ten years. That's not to say that they'll all last that long, and in some instances they may last longer. This all really depends on how well they're taken care of and the environments which they are used in.
So why wouldn't you want to use a normal home refrigerator freezer with a power inverter in your truck, RV or off-the-grid application? Because it's not a good idea! Firstly, because this method creates yet another point of possible failure. When run too hard a power inverter will fail. Aside from that, power inverters are typically very inefficient. This means that the power inverter will consume a lot of DC power just to create a little 110v AC power. In addition to this, home refrigerators and freezers tend to consume much more power than portable 12-volt refrigerator freezers.
Thermoelectric 12-volt coolers are cooled (or warmed) using what's called a Peltier Module. The Peltier Module in short is simply a few thermocouples connected together and sandwiched between two ceramic plates. Each of these ceramic plates must also be in direct contact with a large heatsink and a powerful fan. The Peltier effect is pretty neat for a science / electronics experiment and you can learn much more about the Scientist named Peltier and Peltier modules here: http://www.heatsink-guide.com/peltier.htm.
The Peltier modules used in thermoelectric coolers and warmers consume quite a bit of power to do their job. Portable 12-Volt coolers can typically hold an inside temperature of about 40° below the ambient (surrounding) temperature. Generally they can cool to a low around 40° inside. 12-volt coolers are generally not thermostat controlled; they're either on or off.
What is the typical lifespan of thermoelectric 12-volt coolers? You can expect just about any thermoelectric cooler warmer to give you from three to six months of continuous use. When these are used by campers they will normally be used for a total of a couple of weeks per year. In these cases thermoelectric coolers can last several years. When these 12-volt coolers are used by professional drivers like full-time OTR truck drivers, they will normally function for several months before needing repaired or replaced. This causes several problems. First the driver will normally lose food to spoilage, and secondly the manufacturers of these 12-volt coolers do not offer a full line of replacement parts. The warranty period on most thermoelectric coolers is from three to six months.
Some campers and truck drivers prefer the thermoelectric 12-volt coolers. Some folks never have a problem with their cooler as it operates flawlessly for years and years, and they don't mind the extra power consumption by the peltier module.