Yamaha Battery Management System

Reduce the number of batteries needed on your boat.
Yamaha Battery Management Unit
Reduce the number batteries while increasing charging performance. Courtesy Yamaha

Today’s multi-engine boats increasingly rely on DC power for a host of functions ranging from engine starting and electric controls to onboard accessories and marine electronics. As DC reliance ramps up, so does the need for more batteries. But an innovative system from Yamaha Marine is reversing the trend and offering new benefits.

Yamaha’s Battery Management System (BMS) reduces the number of starting batteries required for triple, quad and quint Yamaha Digital Electronic Control (DEC) outboard installations that incorporate the Helm Master EX system.

In a conventional setup, each engine requires a battery. With BMS, the number of starting batteries is cut to just two.

That translates to more room, less weight, cost savings and neater rigging. At the heart of BMS is the Yamaha Battery Management Unit (BMU) that allows you to turn on the batteries remotely via a button on the Helm Master EX key fob or on the helm switch panel.

BMS eliminates the need to clamber into a dank bilge compartment or squeeze inside a console to throw the battery switches. 

It also lets you remotely turn on deck lights and other illumination. To do this, leave the lights on, then turn off the batteries when you exit the boat. This will turn off the lights. On the next trip, turn on the batteries with the remote fob as you approach the boat and the lights will illuminate as you walk down the dock—a convenience you’ll really appreciate when the schedule calls for a pre-dawn departure.

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BMS also features a smart-charging system that prioritizes the starting batteries to maintain them at or near 100 percent charge. Once the starting batteries are charged—be it via shore power or the engine alternator—the system then redirects charging amperage to the house battery bank. A state-of-charge (SOC) indication on a Yamaha CL5, CL7 or multifunction display (if equipped) monitors the readiness of the starting and house batteries.

Yamaha’s BMS is available largely as a feature on new boats and carries a suggested retail price of $2,200, excluding batteries.