ARCO 12V 55A Universal Alternator, Single Groove Pulley

The ARCO 12V 55A Universal Alternator has a single-groove pulley and terminals for tachometer, indicator light, remote sensing and excitation.

The dedicated terminals are what make this broadly universal, since different engines need different connections. A tachometer terminal drives an engine-mounted tach from the alternator's stator; an excitation terminal starts it charging; remote sensing lets it read voltage at the battery rather than at its own output.

Remote battery sensing is the one worth understanding, because it corrects for voltage drop along the charging cable. Without it the alternator regulates to its own terminal voltage and undercharges a bank sitting at the end of a long run.

It suits Yamaha, Marine Power, Crusader and systems replacing Motorola-style alternators. The alternator is internally regulated with a single-groove pulley, so the belt arrangement has to match rather than being a serpentine drive. Explore more marine alternators.

• Terminals for tach, indicator, sensing and excitation
• Different engines need different connections
• Remote sensing reads voltage at the battery
• Without it a bank at the end of a long run undercharges