Newer cars have a lot of "Keep alive" memory. This includes things like memory seats, preset radio stations, HVAC settings, and all the OBD and computer engine and transmission block learn knowledge. The dealer should be able to tell you based on what is the expected dormant (Not run) time that your car can set by calculating the amp hours of the battery, average temperature the car is setting and the acceptable parasitic load before the car will not start.
What is Kam memory?