Our team has several chargers, but the one I prefer is a
CTEK 3300.
From
it's manual (pdf) ...
"The MULTI 3300 operates in a four step full
y automatic cycle. It starts the charging with an almost constant current (0.8A or 3.3A) until maximum voltage (14.4V or 14.7V) is reached. At this point the charger switches to constant voltage, and the current supply to the battery is gradually reduced. If the current drops to 0.4A, the charger switches to pulse maintenance. If the battery is charged and the terminal voltage of the battery falls to 12.9V, the charger automatically starts again at the first step of the charge characteristic."
Prior to buying the CTEK, our batteries were charged using the Schumacher SC-600A. Using the CTEK, we've discovered several "bad" batteries, with sulphated plates, that were not fully charging.