Based on TP4056, this is 3.7V lithium battery charger modules, with a Micro USB interface. It is small size and light weight, especially for a single lithium battery charging. Features: – Input voltage: 4.5V ~ 5.5V – Input Interface: Micro USB port – Charging method: linear charge – A full charge voltage: 4.2V – Charge Current: 1A (default), modify the onboard resistor to adjust the charging current according to the table below. – Charging accuracy: 1.5% – Charging indicator: Red LED charging, Blue LED full. – Output Reverse: lithium batteries can not be reversed. – Overdischarge Current at 4μA (Vcc= 1.8V). – Precision Overcharge Protection Voltage 4.3V ± 50mV – Two Detection Levels for Overcurrent Protection – Dual channel Enhancement Mode power MOSFET : Due to the internal PMOSFET architecture and anti-reverse charging path, no external isolation diodes are required.