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tsanders2017 asked

Dual Output Alternator from Single Alternator

I am interested in upgrading my house bank from AGM to Lithium. I have a sailboat with four (4) 100AH group 27 AGM batteries for the house bank (12Volt System) and a separate AGM engine start battery. The engine is equipped with a 100 amp Balmar dual output alternator (50 A per leg, one lead to the house bank and the second lead to the start battery) with a MAX charge regulator. The boat has both shore power and an onboard 120v output diesel generator. There is a battery charger aboard that is connected to shore power and generator and this will be replaced with a 2000W inverter / charger). The wire size is 1/0 AWG copper for the line and load side of the battery bank and the connections from the alternator are also 1/0 AWG. I will eventually add solar, but for now I wish to use shore power, generator, and engine alternator to charge the house bank.

* I am keeping the lead acid AGM starter battery for the engine and generator. I believe I need a DC-DC charger for the house bank, which one would normally connect the alternator and regulator to the AGM starter battery, then from the starter battery to the DC-DC charger, then from DC-DC charger to the lithium house bank. However, what do I do with the existing second 1/0 AWG lead from the alternator to the house bank? Is the lead abandoned and the I just use ½ of the alternator? Is there an alternative to a DC-DC charger for dual output alternators?

Any advice is appreciated.


Thank you


Ty

alternator
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1 Answer
Mike Dorsett avatar image
Mike Dorsett answered ·

This really depends on the voltage charge points for the House (lithium) bank and the engine AGM battery. If these are similar - within 100mV, then you can use the dual output from the Balmar regulator, and not need a dc/dc converter. Use the lower of the battery Absorption and float voltages.

If the voltages are too dissimilar to do this, then take both of the Balmar outputs to the starter battery, and use a dc/dc converter.

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