As a person who upgraded his lead acid 48vdc lawnmower to lithium iron batteries 48vdc and had to rebalance the individual batteries using a 12 volt charger, I usually did this when the standard 48vdc charged stopped at about 54vdc. The rebalancing consisted of taking the highest voltage battery reading and charging the other 3 batteries up to that level. But I could have stopped the 54volt charger at anytime and done the same thing. Bring the other 3 batteries up to the battery with the highest reading. The key here is that you need to stop the charging, to find out what all the batteries conditions are.