why does my Volkswagen Tiguan First Generation (2007-2018) battery die overnight when parked

Solution

1. Preparation

• Tools Required: Multimeter, socket set, wire brush or battery terminal cleaner, fuses (as needed for replacement).
• Safety Warnings: Disconnect the negative battery terminal before working on the electrical system to prevent shorts.

2. Replace or Repair Faulty Components

• A. If Battery is Weak:

  1. Remove the battery using a socket set.
  2. Replace it with a new battery if the voltage was below 12.4 volts during the health check.

• B. If Parasitic Draw is Identified:

  1. Locate the faulty component or system causing the draw (e.g., a stuck relay, faulty switch).
  2. Repair or replace the faulty part as needed.

3. Restore Battery Connections

1. Clean battery terminals with a wire brush or battery terminal cleaner.
2. Reconnect the battery terminals, ensuring they are snug and free of corrosion.

4. Test Charging System

1. Start the vehicle and measure the voltage at the battery terminals.
2. If the output is low, inspect and replace the alternator if necessary.