Noelex is correct: almost all modern multi-stage marine battery
chargers use constant voltage for the absorption, float, storage
(in the case of Victron), and equalization
There is no current
limitation on the bulk phase, except for the ability of the battery
bank itself to absorb current
. When the voltage reaches the predetermined level for absorption, then the voltage is held constant at the predetermined absorption phase level.
And, AGMs can absorb a LOT of current. When 50% discharged, for example, Lifeline AGMs can absorb 1.3X rated 20-hour capacity @ 14.4VDC. If voltage is raised, they can take a lot more. And, if they're more deeply discharged, they can take at least 5X the rated capacity.
However, at any given state of charge, a battery will accept what it's going to accept at any given voltage and temperature. No more. Doesn't matter if you use a 1,000 amp charger
, if the battery bank only wants 50 amps @ 14.4VDC, that's all it's going to take.
Battery chargers are voltage limited
in all phases except bulk, though there is a maximum cutoff voltage at which time the charger
goes into the absorption phase. The batteries themselves determine how much current they will accept.