Simple shunt battery balancer

So I want to have a simple battery balancer to balance my lead acid batteries for my ev converted motorcycle. There are 4 12v batteries to balance and my charger is a simple 48v not-even-sure-how-many amp cheap chinese one.



I was wondering if it would be possible to use this circuit as a shunt regulator for the battery, would two zener diodes have to be added in series from the Vi so that only when the battery voltage reaches 13.6V then this begins to shunt. Also what values should be chosen for R1 and R2. Lastly would it be better to add a "dump" resistor in place of the capacitor?


Tyler