[Baeocystin]

My camp cooler is powered by a 60W peltier. Plugs in to any automotive cigarette lighter. It will keep things refrigerator cold for as long as you want, and it's almost completely silent in operation. There's tons of different models on the market. FWIW.

[londons_explore]

You realise how inefficient they are when you load it full of warm beer and run it for a few days and the beer isn't even cool yet. From that 60 watts of input power, you only get ~4 watts of cooling, and with some leaking through the walls of the box, the time to cool down something of substantial mass can be weeks.

That's why you have to use a real fridge to do the work before starting the journey. And at that point, those electric fridges are only slightly more useful than a pile of ice packs.

[RL_Quine]

A couple of watts of cooling is not even enough to overwhelm checking on the beer frankly. All peltier elements are effectively the same efficiency: atrocious.

[Baeocystin]

Obviously, using pre-cooled drinks is better, but if I put in a 12 pack of some beverage, it will be fridge-cold within 24 hours. In practice, it's never been an issue.

[serf]

>It will keep things refrigerator cold for as long as you want, and it's almost completely silent in operation.

that's more a function of the insulation , rather than the cooling ability. The wattage needed for 'thermal maintenance' is far lower than needed for actually removing heat from the system.

Peltiers' are kind of on the same scale of efficiency as using your car (on purpose) to cook food in the engine bay.

[Baeocystin]

...and yet that is still useful enough to be the right answer for some products. For the camp cooler example, it means I don't have to waste precious space on ice packs, nor worry about water as ice melts. If I put in room temperature sodas, they will be cold within 24 hours, which is good enough to be useful. On cold days I can run it in reverse and have a hot drink at break time. And the cooler/heater itself barely adds any weight to the cooler itself.

As a side note, look up the book 'manifold destiny'. It's all about cooking with one's engine bay. An amusing read!