I've played a bit with Sentry Mode, but haven't really found it that useful yet. However, I parked up early yesterday at a train station car park so thought I'd give it a try. 36 hours later, the battery has dropped from 80% to 72%. That's about 7kWh and maybe 25 miles of range. It's an enormous amount to run a dashcam. I notice from Teslafi that the car remains "Idling" rather than sleeping which I guess explains the problem. Means that the computers are drawing about 200W constantly.