welcome to shakanggood Features: Module name: 3S 12.6V Li-ion Lithium Battery 18650 Charger Protection PCB BoardSuitable range: For nominal voltage 3.6V 3.7V lithium battery(Including 18650,26650, lithium polymer batteries) Product size: 59*20*3.4mm Charging voltage: 12.6V - 13.0V Maximum output current: 20A Maximum input current: 10A Precautions: 1.Strictly according to the diagram wiring: 0V/4.2V/8.4V/12.6V,Otherwise it will cause damage to the chip. 2.After connection,it need to first charge activation, then will have the output. Note: Do not mix the good battery and poor battery to use.The internal resistance of 3 battery capacity are closer will be better.Please buyers know the professional knowledge of this module before buying Package Contents: 1 PCS x 3 string 12.6V 20A 18650 lithium battery protection board ************************