USB Meter

Power-down storage function:When power off, the accumulated MAH will be automatically stored. 
The stored MAH is blinking displayed after the boot. 
When the new MAH is up to 1 MAH, the stored MAH will be covered, and the values will start over.
Counting the capacity and efficiency of the mobile power bank battery:
Ah data x output voltage ÷battery voltage ÷ efficiency = mobile power bank battery Ah (output voltage is typically 5V, the battery voltage is generally based on 3.7V, typically by 85-90% efficiency)
Over-voltage and Under-voltage reminding: When the voltage is over 5.3V (less than 4.7V), the arrow will be flashing