For this project, I worked as a marine electrician on a Bayliner 285 at Shepperton Marina, where the vessel’s battery and charging system required upgrading to improve safety, reliability and battery performance.

The existing installation had the engine-start and domestic batteries incorrectly connected through the battery selector switch, effectively combining the banks. Different battery types had also been mixed, preventing the batteries from being used and charged correctly.

I separated the system into a dedicated engine-start battery and two deep-cycle domestic batteries, with each bank connected to its own battery isolator switch.

The existing NOCO Genius 5 charger was also unsuitable for the revised battery arrangement. I installed a Victron mains battery charger for the start battery, with the engine alternator also charging the start battery. A DC-DC charger was then installed to transfer charge from the start battery to the domestic bank.

This provided a simple and cost-effective charging solution without the additional expense of an automatic charging relay or split-charge diode.

The result was a safer and more reliable battery system, with the start and domestic banks correctly separated and both receiving an appropriate charge.