why is my Volkswagen Passat B8 (2015-2022) battery overcharging in hot weather

Solution

1. Preparation

• Gather necessary tools and ensure the vehicle is parked on a flat surface with the engine off.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Inspect and Replace Voltage Regulator

• Inspect the Voltage Regulator:

  • Remove the alternator from the engine compartment (refer to manufacturer service manual for specifics).
  • Check the voltage regulator for signs of damage or wear.

• Replace with New Voltage Regulator:

  • Install the new voltage regulator, ensuring it is securely attached.
  • Reassemble the alternator and reattach it to the engine, tightening bolts to manufacturer specifications.

3. Test Alternator Output

• Reconnect the negative battery terminal.
• Start the engine and use a multimeter to measure the voltage at the battery terminals.
  • Voltage should be between 13.8V to 14.4V. If it exceeds 14.4V, further inspection of the alternator might be necessary.

4. Battery Replacement (if necessary)

• If the battery is damaged or has reduced capacity, replace it with a compatible new battery.
• Ensure the new battery is fully charged before installation.

5. Final Assembly

• Double-check all connections and ensure components are securely in place.
• Reconnect the battery and start the vehicle to confirm resolve.