Battery not charging Audi A6 C7

When your Audi A6 C7 (2011-2018) is experiencing issues with the battery not charging, it can be due to several factors such as a faulty alternator, corroded battery connections, a bad battery, or issues with the electrical system itself. Below is a detailed, step-by-step guide to diagnose and fix the charging problem.

Tools Required:

• Multimeter
• Wrench set
• Screwdriver set
• Battery terminal cleaner
• Diagnostic scan tool (OBD-II scanner)

Step 1: Visual Inspection

• Battery Terminals: Inspect for corrosion or loose connections. Corrosion can prevent proper electrical flow.
• Alternator Belt: Check the condition and tension of the alternator belt. A loose or broken belt can cause charging issues.

Step 2: Check Battery Voltage

1. Measure Voltage:

   • Set your multimeter to DC voltage.
   • Connect the multimeter probes to the battery terminals (red to positive, black to negative).
   • A fully charged battery should read around 12.6 volts when the engine is off.

2. Load Test:

   • With the engine running, the voltage should read between 13.7 and 14.7 volts. If not, proceed to check the alternator.

Step 3: Test Alternator

• Voltage Output:

  • Keep the engine running.
  • Measure the voltage at the battery terminals again.
  • If the voltage is below 13.7 volts, the alternator might not be charging the battery properly.

• Alternator Inspection:

  • Listen for unusual noises coming from the alternator like grinding or whining.
  • Use the OBD-II scanner to check for any stored trouble codes related to the charging system.

Step 4: Inspect Wiring and Fuses

• Fuses: Check the fuse box for any blown fuses related to the charging system.
• Wiring: Inspect the wiring harness between the alternator and the battery for any signs of damage or loose connections.

Repair Instructions:

If Battery Terminals are Corroded:

1. Clean Terminals:
   • Disconnect the battery cables (negative first, then positive).
   • Use a battery terminal cleaner to remove corrosion.
   • Reconnect the battery cables (positive first, then negative).

If Alternator is Faulty:

1. Remove and Replace Alternator:
   • Disconnect the battery.
   • Remove the serpentine belt using a wrench.
   • Disconnect the electrical connectors from the alternator.
   • Unbolt the alternator from its mounting bracket.
   • Install the new alternator and reattach everything in reverse order.
   • Reconnect the battery.

If Wiring is Damaged:

1. Repair or Replace Wiring:
   • Identify the damaged section of the wire.
   • Cut out the damaged section.
   • Use solder and heat shrink tubing to splice in a new piece of wire.
   • Ensure all connections are secure and insulated properly.

Post-Repair:

• Test the System:

  • Start the vehicle and check the charging system again with the multimeter.
  • Ensure all electrical systems are functioning correctly and the battery warning light is off.

• Clear Trouble Codes:

  • Use the OBD-II scanner to clear any stored trouble codes.

By following these steps, you should be able to diagnose and rectify the battery charging issues in your Audi A6 C7. If the problem persists after these repairs, it may be necessary to consult a professional technician for further diagnostics.