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For MS15, some modules had banks with some amount of voltage difference. A few of them were in the range of ~0.5V while others were the highest difference was in somewhere in the range of 0.2V5V-0.3V6V. After taking apart one of the modules with a 0.5V imbalance, we found that there was a single cell in the outlier bank that was dead. We should:
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Determine what caused this issue
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want to know what killed this cell. This Confluence page will outline our findings.
Questions to Answer:
What caused the cell to die? Was it because of:
Spot welding
Connecting a fully charged cell to a fully discharged cell in parallel
Are there any other reasons?
Why is there a 0.2V imbalance between banks in some modules?
Is this also caused by the dead cell, a capacity issue, or something else?
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