Why unblanced cells then balanced the next day? Is it the Soc ?

[Stewfish]

Besides SOC why would there be such a large difference from day to day cell variation?

Yesterday = .59v cell variation
Today = .04v

Yesterday after I saw the cell variation I set the base SOC level to set a level before the Batrium learns the SOC. I moved it to 90% soc down from 100.5%. I set it the first day based on the voltage, but I think I set it low and I know Lifepo4 has wierd voltage vs SOC.

Today was cloudy also, but the first day worries me that I have bad cells or they need to be balanced better, or I am over charging and need to lower the bulk charge, slower charging on a cloudy day, not sure. Later in the day yesterday the Batrium BMS did level off the crazy variation of the cells. Is this just a new pack scenario? Shouldn't new cells be pretty balanced?


They are new Basen cells ordered in March when supplies were legit. I have heard supply issues from Basen since. The system has been running for a few days. They are setup as 48v - 16s2p with Batrium K9 setup to run the 32 cells as 16s2p. The balancing settings are all stock.

The Charge settings are for the lower 90% soc that Will mentions battle born suggests. bulk = 56.1, absorption 54.4

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Yesterday:


Today:

 

[wholybee]

Balancing doesn't mean the voltages are the same, it means the SOC is the same. If you top balanced, then the only relevant point to check if the voltages are the same, is the voltage you top balanced to. They will naturally be very close to the same anywhere on the flat part of the curve, which 90% SOC is.

What it looks like is that the cells simply have not been top balanced. So, especially at high states of charge, one or more cells reach full and run up in voltage before the others. You need to top balance and then the voltages should be 0.01 or better at 100% SOC.