I actually don't think 9°C is cool enough. My TCX21 cools deeper. In summer, the cooling element inside (at the front) even freezes over several days and forms a layer of ice. Perhaps your internal fan is not working properly (mixing of the air)? Have you measured the temperature at the bottom?

Hello bonito The cable is approx. 275cm long including the plug.

I once had the box in the car for about 6 hours in the blazing sun. Of course, the box can't keep the temperature constantly low, but I was still pleasantly surprised at how well the coolness was maintained. All in all, I'm very satisfied and can get by without a compressor cooler. However, if you need a constantly low temperature, you probably can't do without a compressor box.

The connection cable with the plug for the 12V socket in the car (cigarette lighter) is included in the package.

I still have a box like this in my office, but honestly, you'd better buy a compressor fridge. you won't get anything cold with it.

According to the manufacturer's website, the device can be operated with 12 and 24V DC in addition to 230V AC: https://www.dometic.com/de-at/outdoor/essen-und-trinken/kuhlboxen/elektrische-kuhlboxen/dometic-tropicool-tcx-21-31799

15 bottles

Yes, everything is "saved". If the box is not switched off manually, all settings are retained. Also works when changing from shore power to 12 V or vice versa.

As far as I know, TC is an older model. In any case, it looks different in photos. Unfortunately, I don't know whether it differs in terms of technical data. Sorry.