Review on Koolatron P 20 Thermo Electric 12 Volt by William Turner

We've had our Koolatron for four years and usually use it a few times a year for 2-4 hour rides. Pros: It's big enough to carry everything we need for a multi-day trip, yet compact enough to easily fit in any of our vehicles. With the built-in refrigerator, it keeps things cool during transport to the destination. .Cons: Here's the big problem, and it's not at all unique to this product - it doesn't have much cooling capacity itself. After investigating the extravagant claims in some reviews, I ran my own test and here are the results: At a stable ambient temperature. temperature is 72F, the device has reached a steady state internal temperature of 57°F, ie a temperature difference of 15°F. Here's an explanation of why this result is reasonable: Thermoelectric coolers like this one use a device known as a Peltier, which works on the Seebeck effect. These semiconductor devices cause heat to move from side to side in the direction of current flow. Therefore, the heat transfer can be changed by changing the direction of the current, ie by reversing the polarity of the connector, the inside of the Koolatron heats up. This is because "heat" follows the flow of electrons from one side of the Peltier junction to the other. Thus, the amount of heat transferred through the device is proportional to the number of electrons (current) flowing through it. As others have noted, this device runs on 48W (12V*4A). Single-stage Peltier sensors (like this one) typically have a 5% efficiency in converting electricity to heat transfer, which equates to a typical 2.5 watts of heat transfer. So imagine the heat you get when you put a 2.5 watt light bulb in a 1.4 square foot box. This is the amount of heat that this cooler can send in or out. It's physically impossible to create a 45 degree Fahrenheit drop, especially in an ambient temperature above 30 degrees Fahrenheit, when using this technology *at* this power level. So my observed temperature difference of 15F and 72F is pretty good considering what we're working with here. Conclusion: Given the design and the price, this cooler does exactly what is expected. This insulated box will keep things "cold" for (I assume) 24 hours of driving in a warm environment. Think of the electric cooling component more like "wind on the back" of ice packs ;)