I am going to share with you all an observation that I recently made regarding my USB Flash Drive. The brand is probably not too important however I am using SanDisk Ultra Fit USB 3.0 Flash drives in 128GB and 32GB sizes. These are the very tiny USB thumb drives which are just barely larger than the USB interface itself. Now for the observation.... I was removing my drive from my parked and turned off Model S in order to add some new FLAC music files to the drive... Well, when I removed the drive it was actually HOT to the touch even though the music system was paused and off for the last 12 hours. How could this be? What was going on I thought to myself? It appears that the USB drives are powered on by the Model S at all times if they are plugged in. What I found interesting and somewhat alarming, was the heat component that was being generated. My solution was to purchase a USB 3.0 harmonica, with each USB port having an on/off switch. When I get out of the S, I press the button on the USB harmonica and turn the USB drive off. No more heat... No more wasted DC power. And hopefully, less 12 volt battery wear and tear. So, beware all, your USB drives are ON and consuming some power even with the Model S is OFF and the entertainment system is paused.