For when I get my 2009 FXSTC back from HD with the new TSM and 2 new keys. How does the igniton switch work? Why have a key and also a knob? Is it ok to turn the key to on and pocket it and then turn the knob to on or off? Doesn't draw a current like that? Won't run down the battery? I just don't understand the key/ knob thing.