Charging mode IN: By setting the upper limit voltage UP and the lower limit voltage ; when the battery voltage the lower limit voltage , the relay is turned on, and the charger starts to charge the battery; when the battery voltage the upper limit voltage UP, the relay is turned off to complete an automatic charging; the relay is turned on, IN flashes to indicate it is charging. Discharge mode OUT: By setting the upper limit voltage UP and the lower limit voltage ; when the battery voltage the upper limit voltage UP, the relay is turned on and starts discharging; when the battery voltage is the lower limit voltage , the relay is turned off to complete an automatic discharge function; the relay is turned on, OUT flashes, Indicates that it is discharging. Note: This product is a simple voltage controller, the output is turned through a relay, it only plays the role of a switch and cannot change voltage. Color: black Material: PCB+ electronic components 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 modes, 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) , FOP in discharge mode: forced (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 Package Contents: 1 x Battery protector 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.