[Al Skierkiewicz]

Do not try to charge batteries in parallel please. I asked this question of MK and The Battery Association of America (I think that was the name) and both responded that the only way that was acceptable was if the batteries were all purchased at the same time, had been charged the same and had the same loads applied over their lifetime. And then it may work or it may damage all of the batteries. In other words if the batteries were assembled into a larger array and only used that way could other methods of charge and discharge be used. These batteries are not like the large arrays used on electric subs or in large UPSs where the acid is checked regularly and specific gravity is monitored cell by cell.
The best way to test batteries is to use an analyzer like the CBA III from West Mountain Radio. when they can no longer supply more than 15 amp hour, I would move them into the practice pile. When they fall to 10-12 amp hour, then it is time to recycle. If one cell dies before the others, recycle immediately, that cell is likely damaged internally. The Battery Beak from Cross the Road Electronics should also indicate when to remove the battery from competition.