Pontiac Repair: Battery drains, pontiac bonneville, neded

Question
I have a 2002 Pontiac Bonneville.  The battery keeps draining when the car is off.  Took to Advance - thought battery was bad or maybe a problem with alternator...they did a System Check & everything is fine...But...again this a.m. go to start the car and the battery is drained again...and so I have to jump start the car...And, now the Security light stays on...Any idea what could be the problem?

Answer
Hi Annie:

well a few things here. there can be multiple things that are staying on in thi car causing the battery to drain. Is this an sle sse Model? All cars have what is called parasitic draw that uis the amount of current neded to keep the memory alove in all the computers in the car. one of those computers/modules may not be powering down fulling cauing the battery to go dead. How did they check the battery to tell you it was good? you may have a battery that is the original in the car and it's just gotten to the end of it's useful life, it happens. You can also have something drawing it down. Yougoing to have to have this car put on a draw test and see how much of a draw there is on the battery when the car is turned off and all the modules are powered down. As a rule no car should have more than a 25 milliamp draw Which is not much. Anything over that is going to take some investigation as to what the root cause of it is. Does this car have onstar or auto cliamte control? XM radio?? As for the security lamp it may have set a code when you tried to start the car and the battery volatge was low and that may be all that is or it may be something else it could also be related to the draw on the battery.... Hope that helps you out some. good luck :)