I have a question regarding the power usage for the AMI on my 09 a4. I had the car completely off and a USB stick plugged into the adapter. I noticed today while getting something out of my glove box that the light on the usb drive was on, meaning power was going to it. I recently picked up a USB hard drive and I would guess it would use a bit more power. Do I need to unplug it every time i get out of my car? I don't want it to end up draining the battery. Thanks for any info.

-Bob