As shadowman says, it is best if all the batteries are in the same condition. Within one tenth of a volt of each other. In the case of an older pack it may be best to search out a used battery in usable condition. You can go to a battery center or golf cart shop and ask about cores that may be a match for your set. BRING your meter. Good Luck.
PS:
Battery reading should be taken 45 minutes after the charge is complete. This allows the electrolytes to settle and gives a more true reading.
