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

The Blue Sea Systems m-Series Mini 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, 300A continuous, 500A intermittent (5 min)
• 1500A cranking (10 sec), 32V DC maximum
• 3/8" (M10) tin-plated copper studs, torque 120 in-lb (13.56 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 120 in-lb (13.56 Nm). This compact Mini selector fits where a full-size switch won't, with an isolating cover that has snap-in side pieces protecting rear contacts and allowing wire access from any direction, and a case under 3in square. 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.