Balancing problem

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Simo Hassi asked Feb 14, '24

Balancing problem

I have four 25,6 V 200 Ah LiFePO Smart batteries with EasySolar 48/5000 in a solar power system on a boat. Because we normally have no electric network available equalization of the batteries is not possible. However they have kept well balanced until now when one of the batteries is showing imbalance in VictronConnect app.

Now I have brought the boat to electric network and charged the batteries through the EasySolar. After reaching 100% SOC the imbalanced battery still shows imbalance because two center cells have 3,36 V and 3,29 V. I kept charging over night but the EasySolar gives only 30 – 40 W even if it shows bulk mode charging. Perhaps BMS has something to do with this although it's not giving any alarm.

CCGX has a equalization option in settings but every time I try to start it I get ”Charger not ready, equalization cannot be started.” Funny thing is that after over night charging all batteries are now showing imbalance even if their cell voltages are within 0,01 volts except the one that is really imbalanced.

Should I now take the imbalanced battery out and cahrge it separately?

Lithium Battery

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Answer 1 · 2024-02-14T13:32:55Z

Alexandra answered · Feb 14 at 01:32 PM

@Simo Hassi

Is all your firmware up to date.

How is it programmed? Equalisation is not normally used for lifepo4. The absorption stage is where the batteries balance.

If possible charge the one by itself.

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Simo Hassi commented · Feb 14 at 02:42 PM

Hi Alexandra,

Thank you for your answer. All firmwares should be up-to-date. I'm going to take the imbalanced battery out and charge it separately with a Victron Blue Smart charger. Then I don't have BMS available (because I don't want to dismantle it from the boat) but I'll charge outdoors.

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Alexandra ♦ Simo Hassi commented · Feb 14 at 02:49 PM

It may possibly be better since it is a cell balance issue, to charge that one on the BMS with the others disconnected from the BMS.

Are they Victron ones?

If they are then make sure to monitor them like a hawk.

See the manual here.for some precautions.

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Answer 2 · 2024-02-14T18:08:51Z

Michelle Konzack answered · Feb 14 at 06:08 PM

Since the Easy Solar is still charging with 30-40W, from my point of view the EasySolar is still Charging and the BMS of the LiFePO4 Batteries is simply limiting the Charging current not to damage the other cells

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Answer 3 · 2024-05-07T15:53:16Z

Simo Hassi answered · May 07 at 03:53 PM

I took the imbalanced battery out and charged it 24 hours without bms by a Victron charger in Li-ion mode. It got fully charged but still one of the cells showed lower voltage and hence the battery was imbalanced.

After that the battery bank was stored over winter in 60% soc. Last week I took the boat in use after fully charging the batteries. Today bms shut down the Multiplus because the problem cell had only 2.94 volts.

Obviously one the four batteries has a faulty cell. Can it be replaced somewhere or is it just buying a new battery?

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Alexandra ♦ commented · May 07 at 05:21 PM

Are these victron batteries?

If they are then a warranty repair may be possible.

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Simo Hassi Alexandra ♦ commented · May 08 at 07:11 AM

Yes, they are Victron 25,6 V 200 Ah batteries. I purchased them four years ago. How long is the warranty?

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Michelle Konzack Simo Hassi commented · May 08 at 07:19 AM

AFAIK 2 years

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Answer 4 · 2024-05-08T09:51:19Z

klim8skeptic answered · 6 days ago

@Simo Hassi I took the imbalanced battery out and charged it 24 hours without bms by a Victron charger in Li-ion mode.

This does not match what is recommended in the LSB manual . The battery may have to be charged for more than 24 hours to recover a imbalanced cell. And the battery can then only be considered fully charged when Victron Connect reports the battery as "balanced".

Properly fully charge the errant battery, and put it back into service when the other batteries are also fully charged.

Also the warranty for LSB is 3 years (conditions apply).

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Answer 5 · 2024-05-08T14:49:39Z

Simo Hassi answered · 6 days ago

Yes, it's not recommended but possible for a specific reason. In this case the specific reason is that the boat is powered only by solar panels. I'm not living that far north that sun would be shining 24/7. Then the imbalanced battery must be taken out and brought to mains for a longer charging period.

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