The Centerfielder II (CFII-12/24) balances twin engine charging systems by monitoring the port and starboard voltage regulators. When both alternators and regulators are working, the Centerfielder II automatically designates the starboard regulator as dominant for both alternators – making it possible to charge a single house battery bank with the combined output of both alternators. The Centerfielder II eliminates the “yo-yo effect” of two regulators repeatedly turning on and off as the battery approaches target voltage because the two systems are not working in concert.