Keweisi KWS-V20 USB Capacity Tester for Powerbanks
These are perfect USB capacity tester modules so you can measure how much capacity your power bank has left. We also sell the 1a/2a load resistor so what you can do is charge your cell phone power bank fully then plug this into your output usb and then plug the resistor pack into this unit. Just $5 for this unit and $1.50 for the usb resistor. You will have yourself an accurate tester. Super easy to use and has a reset button to start a new test. Just hold the reset button down until everything clears to 0 for a reset. You can also put this in line with your charger to measure capacity of charging.
Voltage ( input / output ) : 3V - 9V
Voltage resolution: 0.01V
Current ( input / output ) : 0A - 3A
Current resolution: 0.01A
Accuracy: + / - 1 percent