how to troubleshoot my Volkswagen Passat B8 (2015-2022) with a dead battery after a short drive

Solution

1. Preparation

• Gather tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is off.
• Disconnect the battery (negative terminal first).

2. Clean and Secure Battery Terminals

• Sub-steps:
  • Remove the battery terminals using a wrench (10mm).
  • Clean the terminals with a wire brush and a mixture of baking soda and water to neutralize corrosion.
  • Dry and reattach terminals securely (positive terminal first).

3. Replace the Battery (if necessary)

• Sub-steps:
  • Remove the old battery from the tray, noting orientation and connections.
  • Place the new battery in the tray (ensure it matches specifications).
  • Connect the positive terminal first, followed by the negative terminal.
  • Ensure the battery is secured with any retaining brackets.

4. Test the Charging System

• Sub-steps:
  • Reconnect the negative terminal securely.
  • Start the engine and check the voltage at the battery with a multimeter.
  • If the voltage is not within proper range (13.7 to 14.7 volts), replace the alternator.

5. Inspect and Replace Alternator (if necessary)

• Sub-steps:
  • Disconnect the battery again.
  • Remove the serpentine belt from the alternator.
  • Unbolt the alternator from its mounting (typically 13mm bolts).
  • Disconnect electrical connectors and remove the alternator.
  • Install the new alternator in reverse order, ensuring the belt is properly tensioned.