I would call the charging rate the current.
The charging voltage at 2.51 V per cell on a 4 cell battery (nominal 8V) should be about 10.04 volt.
If you do not have a good voltmeter then pull the cell caps and in the later stage of the charge see if there is bubbling in each cell. One bubble per second or so is fine and indicates you have the battery up to full charging voltage (TVG Temperature Voltage Gassing). It does need to be a rolling boil.
At approx 3 to 5% of battery ampere rating ie say 100 amp hour referanced to 20 hour discharge (4 hr is also common) then you can shut down the charge. This is NOT the cold crank rating.
Watch battery temperature and shut charge down at around 100 F. At this conservative temp you will do no harm to battery. Let cool and restart charge when cooled down to say 80.
Maker of battery will give you all the more accurate values for that particular battery but these numbers are pretty good to use as guidelines.
At rest say 4 hours after charge termination voltage should be about 2.1 V per cell or 8.4 V
Dan Bentler
