KW203 USB Current Voltage Tester Power Charger Are you still worried about the danger of explosion when your phone is charging? Dont worry. This KW203 USB Current and Voltage Detector can help you master your device easily. Accurate readings, small deviation. Dual USB output ports can support charging or testing for two devices. It can easily measure the output voltage, operating current and the charge - discharge capacity of USB ( PC USB, phone chargers, car use chargers, external power supply etc. ).