Feature:1. MAIN FUNCTION: This MPPT solar charger allows you to transfer the power from solar panels or other photovoltaic devices to rechargeable batteries.2. EASY TO USE: Insert the solar panel into one side of the solar charger, and then insert the battery into the other side to start charging.3. STABLE CHARGING: With the maximum power point tracking function of solar panels, the solar charger board provides complete charging management for a single lithium battery.4. MULTI FUNCTIONS: The constant current charging current is set by an external resistor; Trickle charging of deep discharge batteries; Automatic charging function.5. CHARGING DETAILS: Charging current up to 2A; PWM switching frequency 300KHz; Constant voltage charging voltage 4.2V 1%.Specification:Item Type: Solar Charger Board Material: PCBInput Voltage: 9VFeatures:Output Voltage: Nominal 3.7V full stop voltage 4.2V lithium battery single series lithium battery charging managementInterface: 2Pin PH2.0 JSTMaximum power point tracking function of solar panelsComplete charging management for a single lithium batteryCharging current up to 2APWM Switching Frequency: 300KHzConstant Voltage Charging Voltage: 4.2V 1%The constant current charging current is set by an external resistorTrickle charging of deeply discharged batteriesAutomatic recharge functionIndication of charging status and charging end status.Package List:1 x Solar Panel Module 2 x Connect Cable