Maker Pro
Maker Pro

Car battery charger with funny design ?

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 ?