Why does my Power Bank make a High pitch noise?

[Chintan Dave]

I just bought a 13000mah Power Bank of company Ambrance. Whenever I charge my phone through this power bank, the power bank makes a high pitch noise, not too loud but its annoying. After sometimes the noise suddenly dims away and completely stops!

Is it something to worry about the high pitch noise?

 

[Titillating]

Sounds like coil whine. Most chargers of any kind will produce some form of a high pitch noise, at least from my experience. How loud that noise is depends on the build quality and how well the damping materials are working. Coil whine itself shouldn't be harmful, just annoying.