Battery Not Charging Issue - Audi A6 C7 (2011-2018)

Tools Required:

• Digital Multimeter (DMM)
• Battery Charger (optional, for charging purposes)
• OBD-II Scanner
• Basic hand tools (wrenches, screwdrivers, etc.)

Step 1: Initial Battery Check

1. Inspect Battery Terminals:

   • Ensure battery terminals are clean, tight, and free of corrosion. Clean any corrosion with a mixture of baking soda and water. Use a wire brush if necessary.

2. Check Battery Voltage:

   • Set the DMM to DC voltage.
   • Measure the voltage across the battery terminals with the engine off. It should be around 12.6 volts for a fully charged battery.
   • Start the engine and measure the voltage again. It should be between 13.5 to 14.5 volts indicating the alternator is charging the battery.

Step 2: Alternator Functionality Test

1. Check for Alternator Voltage Output:

   • With the engine running, measure the voltage at the battery terminals. If it’s below 13.5 volts, the alternator may not be charging the battery.

2. Inspect Alternator Belt:

   • Ensure the serpentine belt is not broken or slipping. It should be tight and free from cracks.

3. Alternator Electrical Connections:

   • Check the electrical connections on the alternator for tightness and corrosion.

Step 3: Load Test Battery

1. Perform a Load Test:
   • If available, use a battery load tester. Follow the manufacturer's instructions to conduct the test.
   • If the battery fails the load test, it may need replacement.

Step 4: OBD-II Diagnostic Scan

1. Scan for Diagnostic Trouble Codes (DTCs):
   • Use an OBD-II scanner to check for any related error codes stored in the vehicle’s computer that may indicate electrical issues.

Step 5: Check for Parasitic Drain

1. Parasitic Drain Test:
   • Using the DMM, measure the current draw from the battery with the vehicle off. Disconnect the negative battery terminal and place the meter in series.
   • A typical acceptable drain is around 50 milliamps. Anything significantly higher may indicate a short or electrical component staying on.

Repair Instructions:

Step 1: Replace Alternator

1. Remove Alternator:

   • Disconnect the negative battery terminal.
   • Remove the serpentine belt.
   • Disconnect the electrical connectors from the alternator.
   • Remove the bolts securing the alternator and extract it from the engine bay.

2. Install New Alternator:

   • Position the new alternator and secure it with bolts.
   • Reconnect the electrical connectors.
   • Reinstall the serpentine belt ensuring proper tension.
   • Reconnect the negative battery terminal.

Step 2: Replace Battery (if necessary)

1. Remove Old Battery:

   • Disconnect the negative terminal first, then the positive terminal.
   • Remove any securing brackets and lift out the battery.

2. Install New Battery:

   • Place the new battery in the tray.
   • Secure it with brackets.
   • Connect the positive terminal first, then the negative terminal.

Final Checks

1. Verify Charging System:

   • Start the engine and measure the voltage across the battery. Confirm it is within the 13.5 to 14.5-volt range.
   • Ensure there are no warning lights on the dashboard.

2. Test Drive:

   • Take the vehicle for a test drive to confirm that the charging issue is resolved.

By following these steps, you should be able to diagnose and resolve the battery not charging issue on an Audi A6 C7 effectively.