The charger referenced by Chippie does two of the three charging steps for charging SLAs. It limits the initial charging current(good), but then it stops charging when the battery reaches the "float voltage" (bad).
A proper charger does three steps:
(1) limit the initial charging current to a safe level specified by the battery maker,
(2) allow the battery voltage to rise to ~14.5V (2.42V/cell), hold it there until the charging current naturally decreases to ~10% of the initial charging current used in step 1,
(3) then switch to the float voltage of ~13.2V (2.20V/cell).