This is not abnormal. Please try using a different charging cord or a different outlet to test if the product makes this sound no matter what the conditions are. If you are still dissatisfied, please contact our customer support team.
Engineered to refuel devices up to four timesfaster than conventional charging. Powered by INOV (Intelligent Negotiation for Optimum Voltage) Technology for fine-tuned power output & more optimized charging cycles. Up to 45% more efficient than Quick Charge 2.0 & compatible with a full range of USB connection types, from A to C.