Active battery management means the BMS is always recording data, therefore you can record lifetime operation and cycle-life. Passive only manages balancing when the battery is on, for the time it’s off the cells will continue to self-discharge and could therefore drop below minimum voltage levels without warning or alert.

One downside to an active management system is the need to constantly replace the energy being used by the BMS to monitor the batteries health. This isn't ideal in a boat if only used seasonally, but would be perfect for an off-grid solar system connected to solar panels which would recharge the battery daily.