Parent BMS for 4x 12v LiFePo4 bank

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J S asked Apr 12, '22

Parent BMS for 4x 12v LiFePo4 bank

Hello folks,

In my battery bank setup, I have got four identical 12V LiFePo batteries (non-victron) connected in series into a 48V bank. Each battery here has got its own BMS i.e., the BMS's do not talk, each does it's own thing. As you might guess, the first battery to charge up goes open circuit and so the rest of the bank is not charged up properly. I also have imbalance issues during discharge, between the batteries and I suspect within each battery too.

I would like to have a "parent" BMS over all these four batteries. I suppose this would be a 4S 48V BMS if I am getting the type designation right. Is there such a victron product/solution (except the balancer that is) for this need? If anyone here has been in a similar sitiuation, how did you solve it?

Lithium Battery BMS Battery Balancer

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Answer 1 · 2022-04-12T13:36:12Z

Alexandra answered · Apr 12, 2022 at 01:36 PM

@J S

You are experiencing the problem typical of this setup.

Balancers are a must. Ohms law takes no prisoners. Check out the wiring unlimited by victron.

The other things you can do are to beef up the interbattery connections (go big) and check the current share over the bank.

Lower the charged voltage by 0.2v (as a start) or lower the charge amps to slow down the imbalance between batteries in the bank.

The other thing is usually before installing they need to be fully charged as 12v batteries. And a 12v charger separate can be your best friend.

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Answer 2 · 2022-04-14T04:46:36Z

jjbond answered · Apr 14, 2022 at 04:46 AM

I had the exact same situation, I have 16 100ah Battle Born drop in lithiums, each having it's own internal BMS. They're setup as 4S4P for 400ah at 48volt and I was constantly having one of the BMS's drop out and the entire string crash. I put in 3 of the Victron balancers and also did a good top balance on all of them separately when I installed the balancers. The balancers have been a game changer for me.

https://www.victronenergy.com/batteries/battery-balancer

Jen

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Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

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