Dear ST AutoDevKit Support Team,
I am working with the ST AutoDevKit BMS setup and would like to request your technical guidance before powering the system again, because I want to avoid damaging the AEK-POW-BMS63EN board, the L9963E IC, the AEK-POW-BMSHOLD holder, or the cell sense wiring.
My hardware setup is:
AEK-POW-BMS63EN BMS node board
AEK-POW-BMSHOLD 14-cell holder
SPC58EC / AutoDevKit environment
LG INR18650 MJ1 cells
Rigol DP711 bench power supply used in CC/CV mode for charging, supports up to 30 volts (7 cells constrains)
Rigol DL3021 electronic load for discharge tests
I would like to operate the system with 7 cells only, using the following physical configuration in the 14-cell holder:
First 5 cell positions populated
Middle positions unused
Last 2 cell positions populated
The intended logical L9963E cell mapping would be:
Active cells:
CELL0–CELL1
CELL1–CELL2
CELL2–CELL3
CELL3–CELL4
CELL4–CELL5
CELL12–CELL13
CELL13–CELL14
Unused/dummy channels:
CELL5–CELL6
CELL6–CELL7
CELL7–CELL8
CELL8–CELL9
CELL9–CELL10
CELL10–CELL11
CELL11–CELL12
I understand from the L9963E documentation that the device can manage fewer than 14 cells, but I also found information suggesting that the AEK-POW-BMSHOLD may be wired specifically for exactly 14 cells in series. I would like to confirm the correct and safe implementation for this exact case.
During previous testing, I shorted some unused sense nodes with thin wires in the BMS board pins. The measured DC voltage difference between the unused sense nodes was around 0.02 V, but when connecting or switching the DP711 supply, a sense wire burned and the L9963E IC became very hot. This suggests that the issue may involve the physical holder current path, transient current, incorrect sense wiring sequence, or sense wires accidentally carrying charge current.
Could you please clarify the following points?
Can the AEK-POW-BMSHOLD safely be used with only 7 physical cells installed, specifically using the first 5 positions and last 2 positions? (or is there anyway to make it work??)
If middle cell positions are empty, does the holder provide any high-current continuity across those empty positions, or must those empty cell positions be bridged with current-rated conductors?
Should the unused L9963E cell sense inputs be directly shorted together, connected through resistors, or connected according to another recommended topology?
For the above 7-cell mapping, exactly which CELLx pins should be shorted or connected, and should the unused group CELL6–CELL12 be tied to CELL5, CELL12, or both?
In AutoDevKit Studio / BMS GUI configuration, which cells should be enabled or disabled for voltage measurement, diagnostics, undervoltage/overvoltage checks, open-wire diagnostics, and passive balancing?
Should passive balancing be completely disabled on unused/dummy channels? Is it safe to balance active cells adjacent to the dummy region, especially CELL4–CELL5 and CELL12–CELL13?
What is the recommended power-up and power-down sequence when using the AEK-POW-BMS63EN, AEK-POW-BMSHOLD, a bench power supply charger, and an electronic load?
If the L9963E became hot during a previous miswiring event, is there a recommended diagnostic procedure to check whether the IC or input network is damaged before reconnecting cells or/and the BMSholder?
My main concern is that I do not want the sense wires or CELLx inputs to become part of the main charge/discharge current path. I would appreciate a recommended wiring diagram or exact connection table for a safe 7-cell setup if this configuration is supported.
If the first-5-plus-last-2 physical configuration is not supported with the AEK-POW-BMSHOLD, please confirm the safest alternative configuration, using only contiguous 7 cells, or using a custom 7S holder/harness connected to the AEK-POW-BMS63EN.
Thank you very much for your support.
PS: here some images of the sense part got connected and the other one showing the exposed part that got burn
