This 3.7V Battery Charger TP4056 module is made for charging rechargeable lithium batteries using the constant-current/constant-voltage (CC/CV) charging method. In addition to safely charging a lithium battery, TP4056 BMS Board also provides the necessary protection required by lithium batteries. The TP4056 is suitable for USB power and adapter power supplies. Due to the internal PMOSFET architecture and anti-reverse charging path, no external isolation diodes are required. Thermal feedback of the Protection Circuit automatically adjusts the charge current to limit chip temperature during high power operation or high ambient temperature conditions. The charging voltage is fixed at 4.2V, and the charging current can be externally set by a resistor. When the charging current drops to the set value of 1/10 after reaching the final float voltage, the TP4056 Li-ion Battery Charger Module will automatically terminate the charging cycle. When the input voltage (AC adapter or USB power) is removed, the TP4056 automatically enters a low current state, reducing the battery leakage current to less than 2uA. The 1A Micro USB Protection Board TP4056 can also be placed in shutdown mode when there is a power supply, reducing the supply current to 55uA.