48v bank to 12v bank. How to wire a buffer 12v battery?

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tymonboot asked Aug 12, '21

48v bank to 12v bank. How to wire a buffer 12v battery?

(on Sailboat, all batteries LifePO4) 48v main bank and need to run 12v boat loads (mainly low amps but intermittent high amp(windlass ect). I have a spare 12v 100ah battery capable of 2c continous max discharge. I'm just unsure of how to wire this...

My thoughts so far are let the 12v battery handle all 12v loads and charge battery with victron Orion 48/12 20?

I was going to get two 48/12 20's for redundancy but I'd rather not buy 5 or 6

of the things when I have a more than capable 12v battery sitting idle.

Cheers

MPPT Controllers Orion DC-DC Converters not smart

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Answer 1 · 2021-08-13T07:44:32Z

JohnC answered · Aug 13, 2021 at 07:44 AM

Hi @tymonboot

Your diagram is fine. I do this with the exact-same Orion..

There is a 30A model listed, but 20A works for me into 775Ah of old batts. The 'isolated' model nice on a boat to dodge earthing issues.

You'll need to reset it's output V, a tiny-screwdriver/multimeter job (with batt disconnected). I set mine to 13.5V, a sorta-mid-range charge level.

You might want to switch it on/off. Either with a small switch between the 'remote' terminals and/or by something else. I use an Assistant in a Multiplus, switched by V when daily solar charge to the 48V system is established. More wire, but only tiny ones.

For redundancy, don't overlook just a plain ac mains 12V charger, which you might have lying about. These Orions are reliable as hell.

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tymonboot commented · Aug 13, 2021 at 07:17 PM

Awesome! Thanks so much!

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