The Balmar Digital Duo Charge provides regulated charging current to a secondary battery bank and features preset programs for Gel, AGM, deep cycle and standard flooded batteries to ensure proper charging even when battery types are mixed.  Use for charging start batteries, windlass batteries, bow thruster batteries.  Charge is regulated so the receiving battery only receives the charge it needs.  Unlike battery combiners the Duo Charge only requires small gauge wiring (typically 10 awg) so it is especially useful if the secondary battery is in a remote location.