Blue Sea 120-Amp SI-Series Automatic Charging Relay

The Blue Sea Systems 7610 SI-Series Automatic Charging Relay handles two banks at 120A on 12V or 24V, rated IP67 and ignition protected.

The SI-Series is the smaller and simpler relay against the ML-Series, and 120 amps is what it handles. That covers a standard alternator on a recreational boat. High-output alternators on larger vessels need the ML-Series at 500 amps, and undersizing here means the relay is the limit rather than the charging system.

It combines the banks while charging so both receive current, then separates them when charging stops to preserve the starting reserve. Start Isolation can temporarily disconnect sensitive house loads from the engine circuit during cranking, protecting electronics from the voltage dip.

IP67 waterproofing covers temporary immersion, and ignition protection allows installation in a gasoline boat's engine space. LEDs show combined status and lockout conditions, with a remote LED output for indication away from the relay itself. Explore more battery charging accessories.

• 120A, for a standard recreational alternator
• High-output alternators need the 500A ML-Series
• Start Isolation protects electronics while cranking
• IP67 and ignition protected for a gasoline engine space