My 24 volt controller shuts off at 21.5 volts.
Cutoff should be at, or higher than the lowest per cell voltage, but 23.5 seems way too high! (i.e. 1.75v per cell for SLA's = 21.0 volts)
My pack often sags to mid 22's, and does go lower as the capacity gets lower.
Current setup, 250 watt/24 volt chain drive setup on Jamis MTB, 24 volt, 10 AHr Yesa LiFePO4 pack. 15A controller. (increased to 20A, currently dismantled) (motor sold)
Home built recumbent trike, 350 watt, brushless, geared, hub motor, 36v/10AHr 'Duct Tape' LiFePo4