[folivier]

It looks like Magnum is calling Constant Current mode is typically called Bulk by others, Constant Voltage is Absorbtion, and the Maintain mode appears to be the float mode.
My Victron in Bulk mode charges at 14.4 until the amps are full however long it takes, then absorb at constant voltage of 14.4 for my user set time, then goes into float mode at 13.5 volts. But mine does not restart the Bulk charge until the batteries are depleted below my set voltage. Typically the float mode will charge at a few amps to keep the batteries at 13.5 when needed. So the only time it goes into Bulk, Absorb, then float, will be after the batteries are depleted somewhat (don't remember off hand).
I agree with Richard and think you'll end up lowering the recharge voltage. But a call to Battleborn should clear this up for you.