SmartLithium won't balance

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brad-mc asked Jun 13, '24

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.

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.

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.

i'm wondering if restarting the batteries controller will remedy this?

Many thanks in advance

B

Lithium Battery

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Answer 1 · 2024-06-13T19:01:10Z

Rob Fijn answered · Jun 13 at 07:01 PM

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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Answer 2 · 2024-06-13T19:13:38Z

brad-mc answered · Jun 13 at 07:13 PM

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

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

Many thanks

b

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Answer 3 · 2024-06-13T19:23:46Z

pwfarnell answered · Jun 13 at 07:23 PM

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 commented · Jun 13 at 07:28 PM

Yeah that was my broad understanding too

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Answer 4 · 2024-06-13T19:26:10Z

klim8skeptic answered · Jun 13 at 07:26 PM

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

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 commented · Jun 13 at 07:34 PM

@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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klim8skeptic ♦ brad-mc commented · Jun 13 at 08:06 PM

@Brad Mc the range of voltage disparity in the 8 cells is 'better' than the other batteries!

The only times cell voltages deviate is when the battery is nearly empty, or nearly full.

During charge the first cell to get full will have a voltage rise above the other cells. This is where the cell balancers start work, burning energy off (passive balancers), or moving energy from the highest voltage cell to the lowest voltage cell (active balancers). This takes time for the lowest cell to catch up to all the other cells.

Note: in any battery one cell will always be the first to get full (or empty). Normal.

Your battery is communicating as normal, I dont think a restart would help.

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Answer 5 · 2024-06-14T10:12:08Z

Galin Radoslavov answered · Jun 14 at 10:12 AM

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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Answer 6 · 2024-06-14T14:24:33Z

brad-mc answered · Jun 14 at 02:24 PM

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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