Electrical - alternator connection

[NYSail]

Hello all....A question regarding electrical connections. I have currently 3 battery banks. One that is isolated from the other two battery banks that is located at my bow and is dedicated for bow thruster and windlass, one (bank 1) used for starter and one (bank 2) used for house. As the diagram below shows, from the alternator the power runs to the battery isolator sending charge to the bow battery, and then a wire runs to the starter and connects at main power to starter.

Questions
- Is this a typical set-up or should the alternator wire run from the isolator switch back to
the battery selector switch?
- With the current set-up, I am assuming the battery switch needs to be on both to
charge the house (#2) and starter (#1) banks?

- Also, any opinions...I only use the bow thruster / windlass when the engine is running,
and feel that the battery in the bow is a waste of unused power. I actually never use
my windlass and only use the bow thruster when pulling "into" my slip. I was thinking
about making that battery my dedicated starter battery as well as for the bow thruster /
windlass and attach it to the battery switch #1 and then add my current starter battery
to the house to increase capacity there.

Is this a logical set-up?

Thanks! Greg

 

[Mike B]

The reason the bow thruster and windlass battery is up forward is due to the inherent power losses experienced running current through a wire that long. You'd be asking an awefull lot to run the high amps required all that way. The reverse is true, so trying to use the forward battery to start the engine is also going to put a strain on your electrical system. You'd be better off leaving things as they are and adding an additional battery to the house bank.

 

[Don S/V ILLusion]

Before doing anything else, I'd replace or eliminate the isolator as the voltage drop inherent in these causes your batteries to be consistently undercharged. Use of a combiner and/or eco-charger is much preferable.

 

[Maine Sail]

Before doing anything else, I'd replace or eliminate the isolator as the voltage drop inherent in these causes your batteries to be consistently undercharged. Use of a combiner and/or eco-charger is much preferable.

I agree with Don isolators are not the best way to distribute charging loads. Your system is kind of a mess in that you need to decide which banks to charge and when manually.

If it were me I'd start over and drastically simplify the system with one large house bank, one start/emergency bank with no bow battery bank. With sufficiently sized wire for the thruster & windlass there will be no problem with doing this.

Most power vessels, including the one we owned, with electric thrusters, use large battery cable and batteries in the standard location. Here is a link to Imtra/Side Power's cable sizing guide. Imtra/Side Power Cable Sizing (LINK) For a thruster of your size (guessing below 300 amps) 1/0 wire would be sufficient for a 30 foot run.

Run your alt directly to the house bank, by passing the batt switch, then charge the start battery via a charging relay or preferably an Echo type charger as Don mentioned above.