Dual Engines, Dual Alternators, Dual Batteries...

[KX6D]

I have a 1964 25' Branagat Bay made by Cruisers Inc. It has twin Mercruiser 4-cylinders. It also has a 1/2/1+2 battery switch.

As wired, each battery goes to either position 1 or 2 on the switch. The main cables running to both starters are ganged together on the common terminal of the switch.

All the power for the boat is taken from the same lug on each starter and each alternator also connects to the lug on their own starter.

Here is the question... Are the alternators fighting eachother...AND...is there a better way to wire this up?

The 1/2/1+2 switch is going to be replaced with a new switch and ACR based on this video...
http://youtu.be/B4830QsybbM

I plan on having a single starting battery for both engines and a deep cycle for the house. What I can't get my head around is what to do with the two alternators. Any advice and education would be appreciated!

Dino - KX6D

 

[bruceb58]

Most modern alternators will be able to charge the same battery. Check this link out for various ways to hook things up:
http://www.bluesea.com/support/refe...nt_Wiring_Schematics_for_Typical_Applications

 

[dingbat]

Seperate fuel and batteries maintain the redundancy of twins

 

[KX6D]

I have separate fuel lines , filters, and electric fuel pumps. I have thought about having one starting battery per engine and a house deep cycle. Thanks for the input DB and thanks for the link Bruce!

 

[dingbat]

I have separate fuel lines , filters, and electric fuel pumps. I have thought about having one starting battery per engine and a house deep cycle. Thanks for the input DB and thanks for the link Bruce!

The single largest failure point on a boat is it's fuel supply. Separate fuel lines, filters and pumps are meaningless if you're fuel is coming from a single, contaminated fuel tank.

The second most frequent failure is your batteries. Keep batteries separate with the option to use the house battery to start either motor if need be.