PW4000 Is A 1~4 Cell Lithium Battery Charging Management Chip. Can Operate Within The Input Range Of 4.2V To 20V, With A Maximum Charging Current Of 3A. The Charging Voltage Can Be Configured Through An External Resistor. In Charging Mode, If The Input Is Lower Than The Battery'S Full Voltage, It Boost Charging; If The Input Is Higher Than The Battery'S Full Charge Voltage, The Battery Be At A Reduced Voltage. Product Name: 1S2S3S4S Buck-Boost Fast Charging Battery Charging Current: 2A Power Supply Interface: Type-C Interface Instructions For Use The Voltage Is Connected Through Type-C Or Welding, And The Input Voltage Range Is 4.2~20v. If You Purchase A 1S Charging Module, The Output Voltage Is 4.2V If You Purchase A 2S Charging Module, The Output Voltage Is 8.4V If You Purchase A 3S Charging Module, The Output Voltage Is 12.5V If You Purchase A 4S Charging Module, The Output Voltage Is 16.8V The Number Of Your Own Batteries Must Match The Charging Module, 8.4V 2S The Battery Can Only Use The 2s Charging Module. The Same Applies To 1S, 3S, And 4S. If There Is No Battery At The Output Of The Charging Module, The Red And Green Lights Flash Respectively After The Charging Module Is Powered On, Indicating An Abnormality. If The Red Light Of The Charging Module Is Always On, It Means It Is Charging. If The Green Light Of The Charging Module Is Always On, It Means Charging Is Complete. Note: Different Batches May Have Differences In Product Appearance, Color, And Printed Characters, Which Not Affect The Use Colour:As Shown Material:PCB Package Contents: 1 x Fast Charging Module Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.