RE: 18MZ battery charging
I am thinking of doing this for the just in case situations. The outside of the coaxial plug is 5mm and measures 12 volts DC. I found the plug here but have not tried it. [link]http://www.thefind.com/search?query=dc+coax+plug+center+pin[/link]
I plan to connect this to a standard cigarette lighter plug with a 2 amp fuse. I would only charge the transmitter with the engine off to make sure there isn't any ripple going to the transmitter.