Charging while using Outboard

When running with outboards that have on-engine alternators, the system will control the power output of the alternator to charge either a 24V, 36V or 48V battery bank. The output voltage can be changed with a software update. So start with a 24V trolling motor battery bank and when you upgrade to 36V or even 48V in the future, you can use the existing system.

The alternato temperature in the outboard motor is monitored. if this exceeds a target temperature, the power taken from the alternator is reduced.

With an example 175Hp Mercury outboard, up to 80A of the 85A can be extracted from the alternator.


This is approx 1kW of power.

A 36V 125Ah Lithium array is 4,800Wh. So these would charge from one engine from, say 20% SOC to 100% SOC in 3-4 hours.

240V AC Charging

Simply purchase a 240V AC charge and apply the output to the 12V Junction on the Bi Directional DC to DC. An example is the Victron 30A portable unit: This will take 10 hours overnight to recharge. If at a powered dock, simply pug in.

Running 12V Devices

You can run 12V devices of virtually any power size (up to 3,000W) without the need for a 12V house battery.

The Bi-directional DC to DC will supply power back to the 12V side when the alternator is not charging or cant produce enough power.

Naturally, the 24, 36 or 48V battery bank is being depleted so there is a finite limit. Once you get up and power the outboard, replenishment energy resumes charging the battery bank.

Starter Battery Assist

In the unlikely event that the starter battery is flat, pressing the "start assist" on the Victron Cyrix isolator will deliver up to 250A of charge to the starter battery. In short time, the battery should be able to start unless it is damaged beyong recovery.

Starter Battery Isolator

This is not really necessary but in the unlikely event that the larger house bank array is completely drained, there could then be a drain on the starter battery. The Victron Cyrix prevents this.

Add an Optional Battery Monitor with Smartphone App

The Victron smart battery monitor will not only give you the SOC and voltage of the 36V bank, but also the 12V starter motor and/or the 12V DC bus.


The Victron and Safiery 3kW Bi Directional Buck Boost have a 5 year warranty.

The Safiery Lithium batteries have a 3 year warranty.

SKU MAR122448300
Brand Safiery Package