USB tester DC voltmeter current meters power bank battery capacity monitor QC3.0 phone charger detector, USB meter tester is mainly used to detect USB charging current, voltage, discharge capacity, quantity of electric charge, power, timing and so on. It supports QC2.0/QC3.0,BC1.2, for Phone 2.4A and other quick charging styles of cellphone and chargers. Features : Perfect for evaluating whether or not the computer, USB wall charger, USB car charger are outputting acceptable voltage and current range for the device you are connecting. This Power Meter Tester can plugs directly into any USB socket or cable, which displays on the screen the voltage, current and capacity. It provides you a rough estimate of the capacity of the device you are charging. Unit-in more Safety: Real-time monitoring of charge data, USB monitor will automatically cut off when the device is full charged, makes it controllable and more secure when charging, effectively protect your device. Premium LCD Display: To monitor the parameters on the screen. Comes with three various display modes for your choosing. It allows you to find the charging problem of the USB cables, wall chargers, and car charges more easily. Wide Testing Range & Simple Operation: Input/Output Voltage: DC3-30V, Current Range: 0-5.1A. Symmetrical and reversible connector,plug and play,easy to carry 5-bit resolution for more accurate measurements. The screen can be turned off with one button and has a flip screen function. Thermometer function using high-precision thermistor sensor, celsius and fahrenheit free switching. power-off storage function, which can store capacity and energy data when the mobile power is cut off, which is convenient for subsequent viewing and convenient for capacity energy measurement of mobile power.Note: Other USB testers that do not have a power-down storage function cannot test capacity and energy. Measure the quality of the charger: connect the same load, compare the no-load and the load, the greater the voltage drop, the worse the charger capacity is, the worse the quality; the voltage drop is not obvious or the voltage rises, the load capacity of the charger and the quality be better.