Well most systems are designed to run off the cig lighter socket so all
you have to do is wire them to a permanant live and a negative, I
would take the live to the ignition so it comes on when the keys are
in, I would also add an inline fuse so that if for any reason something
should go wrong it would just blow the fuse.
You can do this with both the sat nav and road angel , if i remember
correctly you can buy a hard wiring kit which means you wont have to
cut any wires yourself.
If in doubt mate give me a shout, wont take more than half hour to do [Y]
Tony