Today I went to a place that was installing GPS for $70. They take your existing GPS and run the wire to an extra auxiliary plug in the back of your stereo. In short I do not have to plug into my cigarette lighter. Its a cleaner look and the GPS turns on and off with the car. I do not see any wires, but the GPS is still mounted to the windshield on driver side. My question is: will this drain my battery when the car is turned off. The person that installed it, assured me that it will not drain my battery when the car is off. I am taking his word for it, but wanted to get feedback to see if anyone else did this type of install or knows for sure that the aux plug in the back will not drain battery when something is connected to it.