I've been reading these messages about reducing the effects of
oversulfation for the past few days and thought I'd throw in my two
cents.
While serving on nuclear submarines in the US Navy (during the 80s), I
was sent to the Navy's Battery School. A lot of time was spent
discussing sulfation, which is a normal part of discharging a battery.
Oversulfation, which is what I think is being discussed here, is
caused by under-charging the battery. Fully charging a battery after
a discharge is the best way to prevent oversulfation. The best way of
reversing oversulfation, once it has occured, is to perform an
equalizing battery charge, which is described (sort of) here:
http://www.usbr.gov/power/data/fist/fist3_6/fist3602.htm#sec2.24
The thing a lot of people don't realize is that the charge/discharge
cycle in itself wears down the plates (they form cracks due to
heating/cooling and lead or lead-oxide starts to flake off). This is
why batteries are rated for a maximum number of charges/discharges.
Trying to keep a battery going after this design life is usually a
losing battle.