Reducing the start-up voltage of a low voltage cut-off circuit
Your Programmable Zener LM431 is not referenced to 0V = Vbat-.  (and poorly drawn )

You have no comparator design or hysteresis.

Start over and define your thresholds for cut-off and turn-on or hysteresis levels and choose a comparator or better, look at BMS IC design choices. 

Define all functions or conditions like what purpose your switch serves and how you protect the battery from undercharge load current and how much memory capacity ( V rise) your battery has when load is switched off.