i ve had problems with that circuit draining my battery, in the past, clock can be a problem, cig lighter too; oh by the way always keep lighter in plug, so you dont accidentally short it out. radios i ve had problems in other models, like the cars that have intricate wires to radio, or too many wires going thru ecm, like radio wires 2,,i mean a radio needs 12v not much more special about that, and makes it much less a problem or effect other circuits.