A minor rant here, so appologies in advance..............
Why can't someone design a Proper DC connector that will : give a good contact area, be self cleaning, be immune from damage thro cheap, Chinese connectors, have a proper strain relief, and last.
Laptop connectors are crap because the centre pin is smaller than the dia of the floating socket, so the area of contact is tiny, so crap for passing power. And its nearly impossible to solder a connector onto a PSU giving out 6A, the cable is to big to get into the housing. The old 1/4" is not bad, but suffers in that it needs a massive insertion force, and not suited to repeated use. The connector used for the OBD socket is prone to the contacts opening out, as above, and dear old GM provides the cigar lighter socket for powering auxiliary items. These are crap, they tend to break contact if you waggle them, and the plugs you buy are so cheap and crap that I don't like using them in case they fuse the car wiring.
Remember the old Radar/Military standard connectors, with individual gold flashed contacts, both the pin and socket were the correct dia, and wiped upon insertion. The housing was such that it locked into place, and could withstand a squaddie's standing on it without damage. OK, they cost about £50 each but.......
Ken