If the Xiaomi Rechargeable Mini Fan makes loud noises while in use, here is a general guide for your reference to troubleshoot the issue:
1. Ensure that there are no objects obstructing the fan blades or the fan guard. Even small items can cause loud noises if they come into contact with the blades;
2. Loose screws or components can contribute to vibrating noises. Check the fan's base, frame, and other components for any looseness, and tighten them as needed;
3. A malfunctioning motor can also cause loud noises. Listen closely to determine if the noise is coming from the motor itself. If the motor seems to be the source of the noise, it may need to be repaired or replaced;
4. Ensure that the fan is placed on a stable and level surface. If the fan is wobbling or vibrating excessively due to an uneven surface, adjust the base or move the fan to a more stable location.
If the above troubleshooting methods cannot resolve your trouble, here might be a hardware issue. Please contact our local official service center or your seller for further assistance. They will help you in this regard.