BMW Repair: Battery drained, bmw 740il, sleep mode

Question
I have a 97 bmw 740il. i don't know "What's wrong with it"?.
For some reason, when i turn on the alarm and let it stays on for a night. Then next morning, my battery drained and i cannot start the car. But if i lock the car manually, then it's fine. What shoulD i do?.


Answer
Sounds like your alarm system is kicking the electrical system out of it's "sleep mode".  This car, after 16 minutes, will drop into a very low current sleep mode.  Something in the electronics is causing it to come out of that.

Take it to a dealer for diagnostic