Charger makes a high‑pitched whining noise even when not actively charging.

Safety first: This is usually not immediately dangerous but may indicate aging components.

• Step 1 – Confirm source: With the cover on, listen to determine if the noise is from the top, bottom, or side of the unit.
• Step 2 – Internal inspection (power OFF): Open the enclosure and locate the auxiliary power supply module. Check for loose mounting or components touching the housing.
• Step 3 – Tighten mounts: Secure the module and any nearby wiring to reduce vibration.
• Step 4 – Monitor behavior: If the noise worsens or is accompanied by functional issues, schedule replacement of the auxiliary power supply module.