I have this one
Halfords | Vacanza by Outwell 24L Coolbox
Keeps food cool while away camping. Have run it off a stand alone car battery for days topped up with a small solar panel, Supposed to be really energy efficient and in keeping with the new European ECO legislation coming into force next year.
Very quiet operating unlike some of the cheap ones.
Comes already with the mains and 12v adapter so no need to buy extras
Is pretty big externally for what you can actually fit into it (just enough for a weekend camping trip)
Also when there is nothing in it. it can tip over with the heavy lid when opened un-cautiously