my BMW 3 Series F30/F31 (2012-2019) has a low battery warning but it’s new, what’s wrong?

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, battery terminal cleaner, torque wrench.
• Disconnect the negative battery terminal to ensure safety while performing electrical tests.

2. Clean Battery Connections

• Sub-steps:
  1. Use a battery terminal cleaner to remove any corrosion on the battery posts and terminals.
  2. Reattach the battery terminals, ensuring they are tight and secure. Torque them to the manufacturer's specifications (typically around 10-15 Nm).

3. Test and Replace Alternator

• Sub-steps:
  1. With the engine running, connect the multimeter to the battery terminals.
  2. If the alternator output is below 13.8 volts, the alternator may need replacement.
  3. Remove the serpentine belt using a socket set and a ratchet to relieve tension.
  4. Disconnect the electrical connectors and remove the alternator mounting bolts.
  5. Install the new alternator, reconnect the electrical connectors, and reattach the serpentine belt.

4. Address Parasitic Draw (if applicable)

• Sub-steps:
  1. With the vehicle off, connect the multimeter in series with the negative battery terminal to measure current draw.
  2. Identify any circuits that are drawing excessive current (typically over 50 mA).
  3. Trace and repair any faulty components causing the parasitic draw.