You lose 1% a day, maybe 3% if parked in a windy location in freezing weather. After a couple of days, the car drops into a deeper sleep unless you insist of connecting via the app to check the status of the car. I've left my Model S'es at the airport for 5 days at a time, with "always connected" ON (i.e. deep sleep disabled, only available on MCU1) and dual Blackvue dashcam running 24/7 off of the 12V supply, no problems.