We do this with variable power supplies at 6V (nominal) in parallel. If doing this with 12V equipment, Charge the four 6V bank to 100% SOC. Attaining a true 100% SOC may take rebooting the charger a few times or floating for multiple days, especially if they are sulfated. Make sure current flowing into the batteries at absorption voltage falls below 1% of Ah capacity or less than about 4A @ 14.4V - 14.8V depending upon your batteries specification.
Now break the bank into two sets of 6V pairs and allow the batteries to rest for 24 or more hours and make darn sure each six volt battery is at an equal voltage. If they are more than about .05V apart you will want to balance them in parallel and charge to 100% SoC. Now you can equalize the pairs individually. I am not a fan of using a "smart charger" to do this and much prefer a variable voltage & current power supply where current can also be limited to the point where the batteries can just barely attain the desired equalizing voltage.
A safer way is to equalize them is to do them individually and only a variable power supply would allow for this. This is considerably safer, especially in the event of an internal shorted cell, which can happen during equalization especially to unhealthy batteries or batteries that are no longer in balance, which can happen with series wired banks..
The start battery does not likely need an EQ but check the SG and it will tell you if any cells are out of balance.
#1 Parallel balance charge them if necessary. Fully charge the batteries. Only equalize a battery after it has been fully charged.
#2 Disconnect DC loads.
#3 If you need to add water only add water to a fully charged battery. If plates are exposed you can add water before charging but it plates are exposed this usually means the batteries have been abused and are on their last legs.
#4 Check SG before equalizing to ensure the batteries SG readings are within a safe spread range to continue. Any cell reading more than 0.50 different than another cell means the battery is shot. Do not equalize this battery.
#5 Bring voltage to desired EQ range and make sure it is temp corrected. Equalize at the lowest possible current that will attain the desired EQ voltage. This creates a safer EQ event should the battery fail during EQing. *If you use hydrocaps they need to be removed for equalizing.
#6 Check SG every hour, temp corrected, and when it stops rising you can technically stop equalizing. Stopping here however does not mean you have removed all the sulfation that is removable or re-convertible, it just means the cells are now balanced. Often 2 - 6+ hours may be necessary to gain all that you can gain from an EQ session. Sometimes two 4 hours sessions a few weeks apart is better than one 8 hour session.
#7 If you are properly charging your golf cart batteries at 14.7V to 14.8V then the need for EQ is less. Critical times to EQ are fall, before winter layup and again in the spring.
