my BMW 5 Series G30/G31 (2017-2024) has a low battery warning, but the battery is new, why?

Solution

1. Preparation

• Gather required tools and parts.
• Ensure safety by wearing gloves and safety glasses.
• Disconnect the negative terminal of the battery to avoid electrical shorts.

2. Inspect Battery Connections

• Sub-steps:
  1. Remove the negative terminal first; then remove the positive terminal.
  2. Clean the terminals and cable ends with a wire brush to remove any corrosion.
  3. Reattach the positive terminal first, followed by the negative terminal, ensuring they are tight and secure.

3. Test Battery and Alternator

• Sub-steps:
  1. Reconnect the battery and use a multimeter to check the battery voltage.
  2. Start the engine and measure the voltage at the battery terminals. If below 13.7V, the alternator may be faulty.
  3. If necessary, replace the alternator.

4. Address Fault Codes

• Sub-steps:
  1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
  2. Retrieve and analyze any stored codes related to the battery or alternator.
  3. Clear codes and perform a test drive to see if the warning reappears.

5. Check for Parasitic Draw

• Sub-steps:
  1. With the vehicle off, connect the multimeter in series with the negative battery terminal to measure current draw.
  2. Ensure the draw is below 50 mA; if higher, identify and disconnect circuits until the draw is acceptable.
  3. Repair or replace any components causing excessive draw.