Technical Service Bulletin 611305 — 2009 BMW 335I

"Discharged Battery: Energy Diagnosis Must Be Performed. The electrical system of BMW vehicles has been subject to an ongoing development process over the last few years. This has led to increased demands being placed on the battery. This document covers important information for the dealer on how to handle ""discharged battery"" complaints. A discharged battery can have various causes, most of which do not concern the battery itself. A failed battery is often the symptom and not the cause. A fully serviceable battery fails when an electrical component causes the battery to discharge; the battery becomes internally damaged and must be replaced. For more information, refer to www.batteryuniversity.com/parttwo-42B.htm For this reason, replacing the battery is not usually a permanent repair. The cause of the discharged battery must be analyzed in order to guarantee a proper repair. In order to properly repair the vehicle the first time in the workshop, it is very important that the diagnostic test plans are performed to completion with all results taken into to consideration. The procedure as outlined below contains information that will guide the technician into properly repairing the vehicle and getting paid for a warranty claim. CAUSE Refer to the ""Procedure"" section of this Service Information for details."