Everybody that ever worked with 12V cigare lighter connections knows that they need something else! You need a solid connection that is not sensitive to movements, with no risk of loosing your power during an imaging session.
The other criteria would be that the system is weather proof (no sparks from dewing or icing up during the night, and that it can stand the required Ampéres of current.
In our astronomy club www.vvscapella.be one of our members Jean Lammertyn designed a system based on the XLR standard for audio conenctions.
All details can be found here