Aopec battery monitor is a module which can monitor voltages on both main and auxiliary batteries current on auxiliary battery and alert when auxiliary battery with over or low voltage states.  It will help you manage your battery system more efficiently.

Display Function---Main and auxiliary batteries voltage will be showed respectively in V/V and V/A display windows when it is started. This is the factory setting. And the green LED is off. After switching windows the auxiliary battery voltage and current will be showed respectively in V/V and V/A display windows. And the green LED is on.

Current Sensing---BM12 uses a yellow LED for indicating the current direction. When the auxiliary battery is being discharged the LED is on else the LED is off. And this current direction indicating function will be working all the time.

Alert Function---BM12 sets a function for the emergency situation. When the auxiliary battery's voltage is lower than 11.5V or higher than 15.5V the buzzer will work for alerting . You can off the alerting by pressing the button which there is a buzzer symbol on it. Also when the alerting function is turned off the red LED will be on.