Wiring batteries on an engineless boat

[scottmacc]

This has been a 7- year build...getting down to the end. 41' LOA cutter sailboat. Installing 2, 90 ah AGM house batteries at this point to be charged solely by shore power via a 40amp pro-sport charger. Eventually I'll be adding solar. No engine but not powerless...I've installed an electric motor from electric yacht that has a completely separate 48vt bank and charger. The pro-sport charger specifies it needs to be wired to two separate banks so rather than wiring the batteries in parallel, I'm using a 1-2-both switch to control them. At least that's my thought at this point until advice sends me otherwise. My question is what to do with the negative from each battery. Will it work to wire them together and then run to the distribution panel? Thanks for your thoughts, Scott


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[Stu Jackson]

Originally Posted by scottmacc

My question is what to do with the negative from each battery. Will it work to wire them together and then run to the distribution panel?

Yes, that's the way to do it. Just like a boat with only an outboard engine. The negative of the system is ONLY the negative of the battery bank. Only revise your thinking a tad: you run the negative FROM the DP to TO battery negative. Subtle...

No inboard engine means your battery negative is THE only negative. Forget about "grounding."

[scottmacc]

thanks Stu. Grounding was another question I've been considering. In researching , there seems to be 50/50 opinion on whether or not to connect the DC distribution panel green to the green of the AC panel.

[Stu Jackson]

Scott, that's another can of worms:

Marine Grounding Systems | West Marine

A little off topic, but a worthwhile "basic" that's been quoted hundreds of thousands of times.

Maine Sail has also written a lot on this.

[smac999]

Originally Posted by scottmacc

This has been a 7- year build...getting down to the end. 41' LOA cutter sailboat. Installing 2, 90 ah AGM house batteries at this point to be charged solely by shore power via a 40amp pro-sport charger. Eventually I'll be adding solar. No engine but not powerless...I've installed an electric motor from electric yacht that has a completely separate 48vt bank and charger. The pro-sport charger specifies it needs to be wired to two separate banks so rather than wiring the batteries in parallel, I'm using a 1-2-both switch to control them. At least that's my thought at this point until advice sends me otherwise. My question is what to do with the negative from each battery. Will it work to wire them together and then run to the distribution panel? Thanks for your thoughts, Scott


Sent from my iPhone using Cruisers Sailing Forum

wire the batteries in parallel. wire both charger wires to the same spot.

[scottmacc]

Originally Posted by smac999

wire the batteries in parallel. wire both charger wires to the same spot.

that's an interesting idea. Though the charger supposedly is able to send the amount of charge needed to each independent battery. It may get as confused as I do.

[a64pilot]

Mine will charge 3 banks, but doesn't have to have three.
It will charge only one, just fine, I'd be surprised if yours requires two banks

[mitiempo]

The outputs of the Prosport have to each be connected to a battery. In a parallel bank of 2 each output goes to its own battery.

From your manual:

[scottmacc]

Originally Posted by mitiempo

The outputs of the Prosport have to each be connected to a battery. In a parallel bank of 2 each output goes to its own battery.

From your manual:

thanks for the reply. My concern was due to the fact that I'm using a 1-2-both-off switch that isn't shown in that diagram. I'm in the boat now as I type and just finished installing the batteries into the system....so far so good....and by that I mean no smoke

[Salty Mike]

Originally Posted by Stu Jackson

Scott, that's another can of worms:

Marine Grounding Systems | West Marine

A little off topic, but a worthwhile "basic" that's been quoted hundreds of thousands of times.

Maine Sail has also written a lot on this.

Thanks for the link, very informative.

[mitiempo]

Originally Posted by scottmacc

thanks for the reply. My concern was due to the fact that I'm using a 1-2-both-off switch that isn't shown in that diagram. I'm in the boat now as I type and just finished installing the batteries into the system....so far so good....and by that I mean no smoke

The 1-2-both-off switch has nothing to do with the charger, which is shown directly wired to the batteries.