Blue Sea Systems HD-Series Selector 4-Position Battery Switch without AFD

The Blue Sea Systems HD-Series Selector Battery Switch lets you isolate battery banks to separate loads, or combine them into one for charging and emergency starts, all from a single 4-position knob. A make-before-break contact design means switching between banks never interrupts power to whatever's running.

Key features

• 4 positions, 500A continuous, 700A intermittent (5 min)
• 1600A cranking (30 sec), 32V DC maximum
• 1/2" (M12) tin-plated copper studs, torque 220 in-lb (24.86 Nm)
• Ignition protected, IP66 rated, one-piece stud design never loosens

This switch does not include Alternator Field Disconnect (AFD). If there's a real risk of the switch being turned to Off while the engine is running, an AFD-equipped version protects the alternator's diodes from damage in that scenario, worth adding if the switch is anywhere an inattentive hand could reach it underway.

Torque the terminal studs to 220 in-lb (24.86 Nm). This HD-Series selector is built for large diesel engines and accepts two 4/0 AWG battery cables per terminal, giving it the highest continuous rating in the family for boats with the biggest charging and starting demands. An optional ICON label kit is available for customized position labeling on most models in this family, and mounting works equally well on a flat surface or a rear panel depending on the installation.

Check the terminal connections periodically for tightness and corrosion, especially on a switch handling this much current — a loose stud is one of the more common sources of resistive heating in a battery-switching circuit that sees frequent use.