Here are the DOE documents I mentioned earlier. They are lengthy. DOE spends billions a year, so get your money's worth.
In **broken link removed** document, there is a nice table on page 20 (of the document, not pdf page) that tells about float charging.
**broken link removed** document describes some of the dangers of overcharging, including production of poisonous gases from batteries that have been modified with antimony, tin, and/or selenium.
I agree with AG. If you are trying to bring back to life batteries that have sulfated, forget it. Also, if the batteries you are dealing with are "sealed," some of the maintenance procedures, particularly with respect to float charging, are different than for flooded, open lead-acid batteries. The DOE documents discuss both types.
John
John