We used a thermoelectric cooler for quite a few of our longer adventures (6 weeks in the Baja, 4 months in Central America). First off, I’ll say that it’s not ideal. It takes a fair amount of battery power, and then only cools to about 22 deg C below ambient in perfect conditions. Further, instead of setting a target temperature, it runs constantly while plugged in. Some more expensive models have thermostats built-in, but really, the chances of getting into the 4 deg C range (typical home refrigerator setting) are quite low. A lot of our food went bad if left for more than a few days.
Size
Our cooler is a 45 litre model. In it we are able to store a few 1 litre nalgene bottles, a bottle of wine, a few beers, enough vegetables for 2 days, eggs, cheese, and a little meat. We can really stuff it full of more things, but at that point it overwhelms the cooling fan, and airflow is restricted. Without air flow it is just a simple insulated cooler that drains your battery.
How Do They Work – The Peltier Effect
Thermoelectric coolers operate on a principal called the Peltier Effect. From Wikipedia the Peltier Effect
occurs when a current is passed through two dissimilar metals or semiconductors … that are connected to each other at two junctions … The current drives a transfer of heat from one junction to the other: one junction cools off while the other heats up …
OK – in plain English: in thermoelectric coolers, the cooling unit consists of a heat sink (an aluminum plate with cooling fins), attached to a thermocouple. When current is passed through the thermocouple, one side gets hot, and one side gets cold. Reverse the direction of current (plug it in backwards) the hot and cold sides reverse. The unit is installed in the cooler with the fan inside the cooler, pushing air across the heat sink. Depending on which way it is plugged in, the heat sink either cools the air or warms it.
What Are The Options?
Keeping your food cool as really important – but at what cost? You can buy really great 12V fridges, operating at really high efficiencies, and you’ll pay between $1000 to $1500. If you’re going on small trips, anything under a week, despite my negative comments, this might be the right thing for you.
Thermoelectric coolers will run anywhere between $75 and $150. If all you need is to keep your milk and meat from going bad, they’re not a bad deal. If we didn’t have it we would have been far worse off. And it was a lot cleaner than dealing with an ice chest, and lot less hassle. If you want to put ice increase the effectiveness, make sure you place it inside a sealed bag. You don’t want melted ice-water ruining the circuits.
If you’re travelling in cold climates, then they’re perfect. We’ve taken ours on winter trips where the weather is below freezing, but while we’re driving the truck is definitely warm inside. If you want ice-cold beers in the summer time, then bring an ice-box, or upgrade to a full scale high-efficiency fridge.
Accessories
Recommended accessories include
- Battery Saver: this will automatically switch off your 12V accessories when it senses battery voltage drop below 11 volts, leaving enough to start the engine.
- Thermoblanket: Purchase one of these to help insulate the cooler.
Photos
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