However the moment voltage is switched OFF across the battery terminals, the battery voltage tends to fall rapidly to some lower value, normally this would trigger the opamp back into its original position and the power would be restored to the battery giving rise to a rapid switching of the output at the threshold levels. The introduction of the 470K resistor eliminates the above possibility and latches the system to a switch OFF position even with the fall in the battery voltage level....however this position is sustained only for some fixed lower level of the battery depending upon the value of the resistor (470k), increasing the value will make the difference less and vice versa.