Two litium bank and solar - DC-DC between litium bank?

Q&A and troubleshooting
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1

On a sail boat. Is it possible to have a litium bank, which is connected too solar with mppt´s and to a AGM battery with a DC-DC 12v 30A. Power to the AGM from the engine alternator.

To have this first litium bank charge another secondary litium bank with a DC-DC between the two litium banks. I think a 12v 50A SMART.

I am only gonna use the DC-DC between the two litium bank when the engine is not running and charging the AGM and the 1. litium bank, so I do not have more DC-DC running in serie at the same time.

Is this possible?

The reason is to have two separate litium bank on the ship, to use two 2000 inverters from 2 different batteri banks. I know a bigger inverter would be better and just one big battery bank. Byt I have two inverters 2000w and one old litium battery bank I don’t want to bye a bigger inverter and many new batteryes.

The first litium bank is 4 x 12v 100A and the second litium is one 12v 314A.

2

Yes it is possible to have a DC to DC between 2 lithium banks.

Do you want the second lithium battery charging all the time or only when the solar is charging the first bank. You will need to vary the engine shutdown voltage settings to make this work to avoid emptying the first battery or not charging the second battery enough. This will be the most difficult part.

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3

Thank you for answering. Have you tried - or is this a theoretical answer?

4

Ot is a theoretical answer based on a knowledge of the products.

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5

Thanks, will trie that on my boat.