Problems with balancing - or just not understanding it. #9
Description
I have added 4 more Tesla module to 4 which I already had in a power wall.
Two modules in series.
Now from the new modules there is one with two cells being 100mV above the others.
When I was charging the whole pack the first time the lowest cell did not go above 3.77V. While the some cells went higher. The highest cell went up to 4.01. Then the BMS shut the charging off because of imbalance.
Balancing was set to 3900mV and soon stopped doing so. So I lowered it to 3500mV and experimented the whole day with short strong charges, strong discharges, slow discharges and right now with a 3A charge which I will leave over night.
What really confuses me is: no matter what I do, the lowest cell never passes 3.77V while charging.
I have attached some diagram and readings from simpBMS the "new" modules are the bottom 4.
Sometimes after burst charges the difference between the lowest and the highest decreased, while still 3.77V was not passed. But after that it increased again on discharge. I'm talking 10mV +/-.
Does it balance on discharge? What are optimal circumstances for balancing? I'm a bit lost here...
