1, the battery of the charging treasure itself is 3.7V, use a 5V charger to charge the charging treasure, and the charging current is controlled by the power management module of the charging treasure. 2, the charging bank to charge the mobile phone, must output the standard 5 V voltage, the output 5 V voltage, by the 3.7V battery of the charging bank, provided, and the control circuit is controlled by the chip (high quality charging bank chip with 8 protection function). 3. Under the control of the smart chip, the output 5V voltage is stable and will not drop. Once the capacity of the power bank is reduced to the 4 indicators are all off, the power bank will cut off and protect the polymer battery in the power bank.