How do you have your VHF radio wired? Do you have to turn the key/ignition on to use your radio or is it wired such that you can turn the radio on without turning on the key ignition? I have to install mine...part of me wants to wire it such that the key is not required so i don't have to hear the beep associated with the ignition and then part of me is concerned the radio will get left on overnight or for a week if we are away and drain down the batteries!!