Blue Sea 300A Black Mini m-Series 4 Position (OFF/1/2/1+2) Battery Selector Switch

Compact High-Current Battery Selection for Dual Bank Systems

The Blue Sea m-Series Battery Switch offers a professional solution for managing two isolated battery banks in marine, RV, and automotive applications. As a 4-position selector switch, it allows you to draw power from Battery 1, Battery 2, or both simultaneously, while also providing a complete disconnect (OFF) for safety and storage. Engineered for systems requiring high power handling in a small footprint, this switch is ideal for switching battery banks to all loads or combining them for emergency starting.

Whether you are outfitting a small boat with an outboard motor, setting up a dual battery system in a 4WD, or managing power in a camper trailer, the m-Series provides the reliability needed for critical electrical connections. Its compact design solves the problem of limited mounting space without compromising on amperage capacity.

Complete Control Over Two Battery Banks

This selector battery switch simplifies power management by allowing you to choose which battery bank powers your engine or house loads. The "1+2" position combines both banks, effectively paralleling them to provide extra cranking amps during emergency starting situations or to charge both banks simultaneously from a single charging source. This flexibility is essential for ensuring you always have a backup power source available if your primary starting battery is depleted.

Safe Switching with Make-Before-Break Technology

Protecting your vehicle's sensitive electronics and charging components is paramount. This unit features a make-before-break contact design, which allows you to switch between battery banks (e.g., from 1 to 2) while the engine is running without interrupting power flow. This feature prevents potentially damaging voltage spikes that can harm alternators and sensitive navigation or communication equipment, ensuring seamless operation during use.

High-Current Performance and Compatibility

Despite its mini form factor, the m-Series is built to handle significant electrical loads. It is rated for 300A continuous current, making it suitable for most marine and automotive DC circuits up to 32V. For short bursts, such as engine cranking, it can withstand up to 900A for 30 seconds. The switch utilises 3/8"-16 (approx. M10) tinned copper studs that provide maximum conductivity and corrosion resistance. These terminals are capable of accepting heavy-duty ring terminals and cables up to 4/0 AWG (approx. 120mm²), ensuring minimal voltage drop even in high-demand setups.

Flexible Installation Options

Installation in tight spaces is made easier with versatile mounting configurations. The switch can be surface mounted, front panel mounted, or rear panel mounted, accommodating various dashboard and locker layouts. It fits standard mounting holes (accepts #10 screws or approx. M5) and includes a snap-on rear cover to insulate terminals, adding an extra layer of safety against accidental short circuits.

• 4-Position Selector: OFF, 1, 2, and 1+2 for versatile battery management
• High Current Rating: 300A continuous, 500A intermittent (5 min), 900A cranking (30 sec)
• Ignition Protected: Safe for installation aboard petrol-powered boats
• Make-Before-Break: Safely switch between banks without stopping power flow
• Heavy-Duty Terminals: 3/8"-16 (approx. M10) studs accept up to 4/0 AWG (approx. 120mm²) cables
• Water Resistant: IP66 rating ensures durability in damp marine environments

Reliable Power Management for Your Next Adventure

Ensure your electrical system is safe, efficient, and versatile with the Blue Sea m-Series Battery Switch. Whether you need to isolate a starting battery or combine banks for a jump start, this switch delivers professional-grade performance.

Secure your power system today with this industry-leading battery selector switch.