When recharging, the battery will get a little hot due to heat radiation, voltage conversions ect. But if you feel it is extremely hot when touching, it seems the battery is abnormal.

Please suggest customer use another equal wall charger and cable to see if the problem persists. If yes, the battery may be defective.

 A higher wattage wall charger will not cause the hot issue if it is working properly. For example, if the input power of the battery is 5V/1A, even you use a higher wattage wall charger at 10W(5V/2A) or 18W(9V/2A), the battery will only accept 5V/1A in charging. It will not be overcharged.