car battery drained from ipod interface?

I hooked up an isimple ipod interface via splicing the audio power wires. Occasionally my car won't start. Would this have anything to do with it or is it something like corroded battery wires?

does the ipod thing work? and did it require u to connect it to the car eletrical system?

yes the ipod works and it does require power from the car. I also have a cell phone charger always hooked up but the cell phone is never hooked up to it so i don't know if that would do anything either.

How is the interface receiving power? And some power outlets are always hot, like the three in my Blazer, so it definitely possible the charger is draining the battery. Unlikely though if there is no phone ever hooked up.