Charging mode IN: By setting the upper limit voltage UP and the lower limit voltage ; when the battery voltage less than or to the lower limit voltage , the relay is turned on, and the charger starts to charge the battery; when the battery voltage greater or to the upper limit voltage UP, the relay is disconnected to complete an automatic charging; the relay is turned on, IN flashes, indicating that it is charging. Discharge mode OUT: By setting the upper limit voltage UP and the lower limit voltage ; when the battery voltage greater or to the upper limit voltage UP, the relay is turned on and starts to discharge; when the battery voltage less than or to the lower limit voltage , the relay is disconnected to complete an automatic discharge function; the relay is turned on and OUT flashes, Indicates that it is discharging. Note: This product is a simple voltage controller, which uses a relay to turn the output. It only functions as a switch and cannot be transformed. Function Description: 1. Calculation of voltage percentage: battery voltage/(upper limit voltage-lower limit voltage) 2. Button function: UP button: Short press to switch display% and time, long press for 5 seconds to switch mode, charging mode: IN, discharging mode: OUT SET button: short press to the currently set parameters; long press the SET button to enter the parameter setting interface, set UP: voltage upper limit, : voltage lower limit, OP: conduction time, : delayed conduction time (0-999 seconds) , There is FOP in discharge mode: forced conduction time (0-10 seconds) DOWN button: Short press to turn off/on the relay enable (emergency stop function) after it is turned off, the LCD display is OFF, and the relay is disconnected Colour: blue Material: plastic Size: 62 x 57 x 22mm Package Contents: 1 x 30A battery charging control module Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.