Charger makes a loud humming or buzzing noise during charging, louder than usual, but continues to operate.

Safety first: Noise alone is not necessarily dangerous, but if accompanied by smell or heat, stop charging and isolate power.

• 1. Identify source:
  • Listen closely to determine if the noise comes from the contactor area, power module, or housing.
• 2. Tighten mountings:
  • With power off, open the housing.
  • Tighten screws securing the main contactor, transformers, and inductors.
  • Ensure housing panels and covers are firmly fixed.
• 3. Inspect contactor:
  • Check for signs of wear or overheating on the contactor.
  • If buzzing is excessive and persistent, consider replacing the main power contactor.
• 4. Vibration damping:
  • Install manufacturer‑approved vibration pads or washers if recommended by Heidelberg.