I have the Sansa dock for the E140 . After a minute without the mp3 player attached it shuts down.richm said:The charging port is always ON. I have a Belkin that works well with my iPod Video. I have left it in another car for days, and it hasn't drained the battery.
Also, I read somewhere that the Sky battery has drain protection. If the battery level falls to the level needed to start the car, it will turn off the accessories.