This is an alarm that will trigger when the voltage of one cell in a battery get below 3.4V.
In this case:
3 cell li-po battery - 3,3 pr cell is the limit.
So the alarm have to trigger at 3.4 to give some time to get the vehicle on the ground.
The alarm is illustrated by a diode. It is possible to change it to a siren.
It is to be used in a quadcopter or a RC aircraft.
