IR matching more important for parallel and capacity more important for series groups?
Cell series assembly - voltage criteria
At the end of capacity measurement, we charge the cells to a known storage voltage, so the cells should be within a tight range already.
All other cell parameters equal, series voltage difference is a least important criterion, as any imablance will be catched up by the BMS during charging.
As balancing speed is limited though, this imbalance should be kept small. Ideally, balancing should be OK after charging the assembled battery once.
Tests to be conducted, value TBD ⇒ 3.6V as storage voltage
Cell parallel assembly - voltage criteria
At the end of capacity measurement, we charge the cells to a known storage voltage, so the cells should be within a tight range already.
With 25mOhm cells, current between cells 100mV apart should be less than 2A during a short time, which is acceptable
100mV range, or +/- 50mV, should be a good value
Tests to be conducted, value TBD
Cell parallel assembly - capacity criteria
Cell parallel assembly - IR criteria
Cell parallel assembly - voltage curve criteria
Voltage curve between different cell models can vary wildly, particularly at low SOCs
Here are some different cell’s curves compared, OCV vs SOC :
