Bluewater 12V 140-Amp Automatic Charging Relay

The Bluewater 12V Automatic Charging Relay handles alternators up to 120A, rated 120A continuous and 140A intermittent, IP67 and ignition protected.

Under-voltage lockout is the protection worth understanding here, and it prevents a specific failure. The relay will not close when battery voltage is too low, so a healthy bank never gets dragged down trying to recover a flat one. Without that lockout, one dead battery can leave a boat with two.

Start Isolation temporarily disconnects house loads during cranking, protecting sensitive electronics from the voltage disturbance an engine start produces. That dip is what damages chartplotters and audio equipment gradually, and the damage is never obviously traced back to it.

Dual-color LEDs indicate charging, discharging, combined operation, Start Isolation, override and other states rather than a single status light. IP67 waterproofing and ignition-protected construction suit an engine space on a gasoline boat, with 120A continuous and 140A intermittent capacity. Explore more battery charging accessories.

• Under-voltage lockout stops a flat bank dragging down a good one
• Otherwise one dead battery becomes two
• Start Isolation protects electronics during cranking
• IP67 and ignition protected, 120A continuous