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brad-mc avatar image
brad-mc asked

SmartLithium won't balance

Hi There,


I have 4 x 24v/100Ah batteries in parallel on a boat with the Lynx Smart BMS. We spend most of our time offgrid relying only on solar. The batteries will often move between balanced and imbalanced.

img-1507.png

However we have just arrived in a marina for hurricane season and been plugged in for a week. 3 batteries have moved back to 'balanced' but one remains unbalanced and proclaims to not have had a full charge for 100 odd days.


img-1508.png


Is this an issue, an early sign of a problem?

The individual cell voltages do not look like anything to worry about , in fact a 'balanced' battery - has a wider range of cell voltages.

img-1509.png i'm wondering if restarting the batteries controller will remedy this?

img-74cedc325f6c-1.jpeg



Many thanks in advance

B


Lithium Battery
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6 Answers
Rob Fijn avatar image
Rob Fijn answered ·

Hello Brad, with the information I see... The charge voltage need to be going up higher and stay for some time high (28.4). In the books you find sometime for 1 hours and some time for 2 hours...
How have you set your Charge profile? Absorption voltage and time ?

regards, Rob

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brad-mc avatar image
brad-mc answered ·

Hi Rob, Many thanks for coming back. i thought there was a preset for lithium batteries, prehaps it was in the MPPT. but this is the current settings on the Lnyx BMS


img-1511.png


Do you feel that i should up the charged voltage to 28.4 from 28.0?

Many thanks

b


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pwfarnell avatar image
pwfarnell answered ·

The charged voltage is not the charging voltage, it is the voltage that the shunt uses to consider that the batteries are charged. It will not affect the voltage they are charged to. As far as I know, the Lynx BMS always uses 28.4V for absorption and is not user configurable and the Lynx BMS sets the charging on the other Victron chargers through DVCC on the GX device.

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brad-mc avatar image brad-mc commented ·
Yeah that was my broad understanding too
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klim8skeptic avatar image
klim8skeptic answered ·

@Brad Mc Victron Connect is pretty clear as to why the battery is "imbalanced", and how to remedy that.

vc-batt-status.png

The LSB manual goes into further detail on why this has happened (The battery has not spent enough time in the absorption charge stage.) and how to recover the cell imbalance (Charge the battery, hold the battery at the absorption voltage until Victron Connect reports "Balanced")

Also read chapter 8.3. Cell balancing of the manual.


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brad-mc avatar image brad-mc commented ·
@klim8skeptic thanks for that. Yeah i have read all that. i was surprised to see the 4th battery not establish the status of balanced. I'm wondering if restarting the controller on the battery will somewhat reset it as the parameters of the battery do not seem to warrent the status. It has been fully charged several times in the last 30-40 days, is currently plugged into shore power and the range of voltage disparity in the 8 cells is 'better' than the other batteries!
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Galin Radoslavov avatar image
Galin Radoslavov answered ·

Hi,

Try to discharge to 50 % and charge again. And high voltage must be 28.4 V and the second voltage 27 V.

All batteries return to normal after this procedure.

And it is not normal 99 days to keep them unbalance. You have to discharge min every 30 days.

Regards.

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brad-mc avatar image
brad-mc answered ·

Success - on the Lynx Smart BMS i reduced the repeated absorption interval to 2 days, just to trigger it and the absorption time to 4 hours. This initiated an absorption period and it ran long enough to achieve the desired outcome for all batteries.

I assume that as these are offgrid batteries and we do cycle them a lot that this extra time was necessary to get all 4 lined up.

Now that all batteries are 'balanced' and have a 'last fully charged' that is realistic i moved the interval to 28 days and the absorption time to 3 hours.

Many thanks to all for the comments and ideas!

b

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