For my Megawatts in an off-grid environment. I try to time the 1st stage to remain at 14.8 volts for 2 hours after attaining 14.8 volts. By choosing a 4,6,8 or 12 hour timer the charging time is set in proportion to ampere hours. One group 24 gets the 4-hour intermatic while 4 golf car batteries get the 12 hour windup. Too much gen run time!
The "secret" is to find out WHEN the batteries start to bubble THEN establish gen surplus run time needed to revert the electrolyte.
From 12.13 volts by saturation charging I can half percent the 31 XT in 2 hours 16 minutes.