Hello!
I have a L9963E in 192 cell EV battery setup, there's 16 modules daisy chained, each handling one 12S pack. The bottom module has a L9963T and stm32 chip that handles the whole pack and communicates with car through CAN bus. Everything is working!
However I noticed that every module reports slightly lower voltage for cell 7 (Vcell 9 in L9963E). This is the cell that sits right next to the "middle gap" where I have two unconnected cell inputs. VCELLx_EN is "0" for those two cells.
RLEC 0 (=0):
Volts: 2971 2969 2971 2969 2969 2967 >2925< 2967 2971 2969 2964 2940
Temps: 21 21 21 21 21 21 34
faults: 00 timeout: 0
RLEC 1 (=1):
Volts: 2979 2979 2979 2979 2976 2979 >2945< 2979 2979 2981 2979 2971
Temps: 21 21 21 21 21 21 30
faults: 00 timeout: 0
Volts are in mV. Left side is lowest cell (Vcell1), right side is highest (Vcell14). As you can see the cells marked with > < have about 35-40mV lower voltage than the rest. Also the rightmost cell is slightly lower but not that much. In reality when measured with multimeter, all the cells in module are within +-2mV.
What is causing this? I think I have the unused pins connected correctly in the schematic (see below). Unused pins are shorted together and connected to the lower cell through 1k resistor, as instructed in the datasheet.
I haven't yet charged the battery to see what the difference is fully charged, but I feel 40mV error in the top end can be catastrophic. I can "fix" it in software but that's of course not ideal.
