Mains & 12 Volt cooler box's are very popular for the camping industry as they are small, light & most of the 12 volt coolers are low wattage. They range in price, capacity and quality.
Many don't know that the most popular and cheapest types of cooler box's (Thermoelectic) work on ambient temperature which means that the box has a fan that sucks in the air temperature that surrounds the box and then depending on the quality of the box you purchase it can reduce that air temperature by either 15, 18, 20 or even 30 degrees below that ambient temperature.

Therefore on a cold day these boxes will be very good but on a warm day they will not. Many consumers are swayed to purchase the cheapest box and not take into account how cold it will go. Read the information below which will give you an insight into Mains Coolers.

Compressor, absorption or thermoelectric?

How you intend to use the fridge will determine what type you'll need.

Compressor portable fridge:

These models operate in the same way as your home fridge. They run on a 12V battery or from 240V AC mains electricity, usually by using an AC adaptor. This type is the best option for most people.

PROS

• Generally work better than the thermoelectric or absorption types.
• Stay cold under a wide range of ambient temperatures.
• Much less of a drain on a car battery during normal running.

CONS

• Setting the temperature and maintaining it once the ambient temperature changes can be problematic. Food can freeze or become too warm if you don't change it.
• You may need to buy an AC adaptor separately if it doesn't come with one.

SCENARIO – REGULAR CAMPERS

The Marshall family like to hit the road as often as they can and find a spot to pitch their tent. They sometimes stay in caravan parks or camping grounds with powered sites, but not always. They've set up their car with a dual battery system and wired a compressor camping fridge into the second battery. That way power is provided to the fridge without causing car-starting hassles. George is also a keen fisherman and uses the fridge to store his bait –

Absorption portable fridge

If you're keen to connect to gas, an absorption model is your only option. It doesn't have a motor and this type needs to sit level and have a heat source, which can be from a car battery, mains electricity or LP gas.

If you're camping for a prolonged period or you're in a remote location, being able to use gas as the power source can be handy.

SCENARIO – REMOTE CAMPERS

The Princes are serious campers who like nothing better than to spend time in fairly remote locations. They find an absorption fridge best suit their needs. They make sure everything is cold first at home before they set off, and then run the fridge/freezer off the car battery while getting to their destination. Once there, they switch over to LP gas. If they're travelling on rough and hilly roads it doesn't work very well, but it's better than nothing, and it works well once they've stopped and have set it up level.

Thermoelectric portable fridge

This type is really designed for short-term refrigeration or keeping warm. They generally have limited cooling ability and are a substantial drain on the car battery. They are quite noisy and are about the size of a small insulated cooler.

When we've tested these types in the past, we've found none of them were able to maintain a temperature that's adequate to store hot food safely.

As for their cooling abilities, we've found some are unable to cool to an adequate temperature once the external temperature gets to about 25°C. So on a hot summer day, a thermoelectric portable fridge probably isn't going to be up to the task of keeping your food and drinks cool. A Igloo cooler  with ice or ice packs may be more effective for a few hours at least.

Don't be tempted to add ice to a thermoelectric cooler as manufacturers warn against it.