Audible buzzing or chattering noise from KEBA charger during charging

Safety first: Isolate power before touching or tightening internal components.

Steps:

• 1. Localize the noise: Carefully listen to identify whether the sound comes from the main contactor, a relay, or another component.
• 2. Check mounting: With power off, ensure the contactor is firmly mounted to the backplate and that any anti-vibration pads are in place.
• 3. Inspect terminals: Tighten all terminals on the noisy component to prevent vibration.
• 4. Measure coil voltage (qualified person): During operation, verify that the contactor coil receives the correct, stable control voltage. Significant fluctuation may indicate a control issue on the main board.
• 5. Replace contactor: If buzzing persists and the contactor is old or shows signs of wear, replace the main contactor.

Mild humming can be normal, but loud chattering indicates a problem that should be corrected.