Blue Sea 9159 m-Series Battery Switch Paralleling Link Bus 2-Pack

The Blue Sea 9159 m-Series Battery Switch Paralleling Link Bus 2-Pack provides a critical interconnection solution for dual-battery marine electrical systems. This paralleling link bus allows you to safely connect two battery banks during engine start while isolating them during normal operation, preventing drain on the reserve battery and ensuring reliable backup power when you need it most.

Built from tin-plated copper with a continuous rating of 250 amperes DC, the 9159 m-Series bus handles the high current demands of modern marine engines and electrical loads without voltage drop or heat buildup. The tin-plated construction resists corrosion from salt spray and moisture exposure—a critical consideration on the water where copper oxidation can degrade electrical performance over time. The compact design integrates seamlessly into Blue Sea Systems' m-Series modular switching ecosystem, making it an efficient choice for upgrading or expanding battery management on fishing boats, cruisers, and offshore vessels.

This 2-pack is ideal for boat owners who run multiple battery banks—a standard setup on vessels with electric trolling motors, winches, radar, sonar, and cabin systems. By isolating the auxiliary battery from the starting battery, you maintain engine start capability even if house loads have discharged the secondary bank. The 250-amp rating supports large-displacement engines and high-demand electrical architectures without compromise, making it suitable for both freshwater and saltwater applications where system reliability directly affects safety and functionality on the water.