A different LFP imbalance problem

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Simo Hassi asked Mar 23, '23

A different LFP imbalance problem

I have charged two brand new Victron LiFePO4 25,6V/200Ah Smart batteries separately in order to connect them in series for a 48 V system. Charging setup includes Blue Smart IP22 24/8 charger, SmallBMS and Cyrix-Li-Charge 24/48-120. One of the batteries was charged and balanced OK.

The other battery was charged OK in terms of voltage but it still indicates imbalance in VictronConnect. Also last full charge is "Unknown" even if the charger had after bulk and absorption reached storage status. Maximum voltage difference between cells is only 0,01 V. Obviously this battery is in fact well balanced but it doesn't appear in VictronConnect. How could I wake up its "balanced" status?

Lithium Battery

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Answer 1 · 2023-03-23T08:38:24Z

klim8skeptic answered · Mar 23, 2023 at 08:38 AM

@Simo Hassi give your battery another charge cycle. It needs to spend some time at 14.2v while the cells even out their voltage.

The BMS might cut charge until cell voltage is stable.

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Answer 2 · 2023-03-23T12:07:00Z

Simo Hassi answered · Mar 23, 2023 at 12:07 PM

In fact I already gave another charge cycle the and imbalance stands. I reckon it should be discharged and then recharged. Just now I cannot do that because the batteries are for an electric boat and our waters are still ice covered. I must wait for couple of weeks.

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klim8skeptic ♦ commented · Mar 23, 2023 at 01:08 PM

@Simo Hassi as per Smart Battery Manual it might take several charge cycles to fully balance your battery.

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Answer 3 · 2023-03-23T13:15:47Z

Simo Hassi answered · Mar 23, 2023 at 01:15 PM

I just wonder why is the battery indicating imbalance when cells are clearly balanced with only 0,01 V difference in voltage?

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klim8skeptic ♦ commented · Mar 23, 2023 at 01:35 PM

@Simo Hassi as per my previous post, the cells will only be balanced at the batteries absorption voltage.

Cell balancing as per manual.

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