[Al Skierkiewicz]

OK Sammy,
We will be waiting for a report in January. There is a possibility that you have one or more failed chargers and that in the normal course of events, all batteries have been touched by the bad charger. That is unfortunate but should not be ruled out. I am going to guess that the batteries have been used often and are just dying of old age.
Doug, the glass is a woven mat between the plates so there is really nothing to break. The lead plates can become dislodged with abuse and break off the common terminal inside a cell. In this case, the battery will test normal even with a momentary load tester. The CBA will show this damaged cell by a drop of 2 volts after a period of time. Black in the attached plot is a normal (2 year old) battery showing 16 amp hour capacity, the blue shows a two cell failure, green shows a single cell failure and the red shows the signs of intermittent plate connections within a cell followed by several cell failures.