I notice most of the car battery charger circuit which using SCR to control allway put one adjustable resistor connected in series to the gate of the SCR,I found it does't make sense,because when the battery was fully charge the SCR will cut off the current, but when you adjust the resistor it will continue to charge the battery again, moreover the circuit design have been consider the resistor value when the battery was fully charge at 13.5 volts. Does any person have any comment on this topic ?