Well operating switches are essential to ensure minimal resistance and power drops. Here we have chosen the Blue Sea m-Series Battery Switches, for Engine Power, Domestic Power and Windlass Power. The m-Series switches are rated for up to 300 Amps of continuous current which is more than enough on our 37 foot sailing yacht.
Top switch for Windlass, middle switch for Domestic and the switch at the bottom for Engine.
As part of the switch installation, we also decided to improve the setup by adding a combine switch for the engine starter. It has three positions, 1 – off, 2 – on, 3 – combined. This way in an emergency the engine can be started using the domestic battery bank which is considerably larger than the starter battery and should in general have no problem getting the engine running. Even if the starter battery is completely flat.
Note that here the windlass takes power from the starter battery. In this setup, it is assumed that the engine will always be running when operating the windlass. The reason for this is that the windlass consumes a large amount of power and may deplete the batteries if no charge is applied during its operation.
If combined operation is not engaged there is no direct connection between engine power and domestic power. The domestic bank charging is made possible from the engine alternator via a DC to DC charger. This ensures complete battery separation and effective 3 stage charging using a Mastervolt Mac Plus 12/12 50 DC DC charger.
Blue Sea switches can be found here:
https://www.bluesea.com/products/category/11/37/Manual_Battery_Switches/m-Series
If you have any questions or would like to know more then please leave a comment below!