As the charger senses the voltage rise and change when your batteries have reached a full charge, they will then automatically switch to compensation charge for about 30 minutes then to trickle charge which will keep your batteries fully charged until use. (Logic Battery)

The current rates used for trickle charging batteries are critical in maintaining a full charge and in preventing an overcharge condition. The importance of the trickle charge rate comes from the design, maintenance and operational requirements of an electrical power system. (Smithsonian Astrophysical Observatory )

Whether you are charging a new battery for your personal watercraft or plugging some juice into an old one over the winter, trickle-charging is the only method to use. (Boating Life)