BMW Repair: Dead battery, negative battery cable, jumper wire

Question
I own a 02 Bmw 530I 74000 miles on 04-20-06 I went to start the car in morning. The battery was completely dead.My mechanic told me I need a new bat  There was no indicaton on the dash lights that the bat was not charging. 09-11-06 battery dead again The mechanic sold me a alternator. Again no indication from the dash warning lights. I finally concluded the car sometimes does not shut down completely. Thus draining the battery by morning.What do you think the problem is Thanks Steve Wolf

Answer
Steve, was the battery replaced? You need to check to see if the car is going to sleep and not drawing too many amps.
You must perform a closed circuit current draw test. Once the body control module (called 'General Module' last one to sleep) goes to sleep 16 minutes after last vehicle input. The orange gear selector LED will go out when the GM finally goes too sleep. You must measure the amperage draw of the sleeping car. The specification is 40 milliamps maximum. Realistically you'll have about 20mA maximum.
You need a professional style Multimeter so you may need a Technician to do this. Car must remain asleep. If the LED turns on the car woke up... GAMEOVER. Start again. To perform the test open passenger door and manually lock door latch. Open glove box. Open trunk and manually lock trunk latch. Access battery. Use a jumper wire with alligator clip ends and attach one end to the negative battery post. Attach the other end to a good chassis ground (you've created a parallel battery ground) Wait untill car goes to sleep (LED off). Set Multimeter so you can read Milliamps. Attach one end to the good chassis ground and the other to the negative battery post. Remove the negative battery cable end attached to the car (13mm nut, not the end on the negative post). Half the vehicles amps should flow through the meter and the other through the jumper wire. Remove one end of the jumper wire. All amps now flow through the meter. Must me around 20mA. If over 40mA you have an excessive current draw. If you get this far send me another post and I will give you further instruction.
-Evan