The simplest way would be to add extra insulation elements to the inside of the cooler. Thus, you can make the temperature even colder, and you can potentially use it for a little while after you’ve unplugged it. You can also replace the Peltier device inside for a better/more powerful one.

All thermoelectric coolers operate based on the so-called Peltier effect. Without getting too technical, the cooler should be plugged in. When the electricity runs through the device inside it, one side absorbs all the heat, while the other gets colder and vice versa.

Honestly, they are potentially even better at freezing and cooling, as they have a constant power supply, which keeps a consistent temperature. The best ones can go down to 35F (1C).

It’s obviously the Dometic Tropicool Thermoelectric Cooler, as it is worth every cent! It is durable, portable, and can keep your food cool regardless of the room temperature.

Thermoelectric coolers are fairly nice. They have the isolating characteristics of a conventional cooler, but they use a solid-state device (driven by electricity) to maintain cold items, unlike simple ice coolers.