This "Low Voltage" version of the standard EN-VSR1224-140 has lower trigger points for both the Turn On and Turn Off.  When the engine is started, starting and auxiliary batteries are separated allowing only the starting battery to be charged. When the charge voltage reaches ≥12.7 volts the VSR engages allowing both starting and auxiliary batteries to be charged. When the engine is stopped and the battery voltage falls below ≤12.3 volts the VSR disengages separating the start and auxiliary batteries.