If Battery Voltages is Less than the Threshold Values then Circuit should stop

How to find hysteresis of the battery ?

I am not using any comparator circuit. I'm just using a step down dc-dc converter XM1584 Voltage Regulator IC which directly connects with the 12 volts Battery at the input and at the output with the Arduino 5 volts. The motors are directly connected with the Battery (both positive and negative) and its both signal pins are connected to the Arduino pin 5 and 6 digital PWM pins. Also I'm using MAX232 IC for interfacing my external radiolink to the arduino for wireless communication ...

Yes you are right because I'm monitoring my battery voltages and its varies gives different values means that 11.61, 11.54, 11.58, 11.62 and soo on ...
Can you please help me to calculate hysteresis of the battery ?