why does my BMW 5 Series G30/G31 (2017-2024) battery die when parked

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, ammeter, basic hand tools (sockets, wrenches).
• Disconnect the negative battery terminal to ensure safety while working on the electrical system.

2. Address Parasitic Draw

• Sub-step 1: Reconnect the negative battery terminal after measuring the draw.
• Sub-step 2: Pull fuses one by one from the fuse box while monitoring the ammeter until the current draw drops significantly.
• Sub-step 3: Identify the circuit causing the draw by determining which fuse corresponds to the reduced current.

3. Repair Faulty Components

• Sub-step 1: If a specific component is identified (e.g., interior lights, electronic modules), inspect and repair or replace it as necessary.
• Sub-step 2: For faulty wiring or connectors, repair any damaged insulation or connections to eliminate shorts.

4. Battery Management System Recalibration

• Sub-step 1: If the BMS is malfunctioning, follow the manufacturer’s service manual to recalibrate the system.
• Sub-step 2: Connect the OBD-II scanner and reset any stored codes.

5. Final Check

• Sub-step 1: Reconnect the battery and confirm that all electrical components function correctly when the vehicle is parked.