simpBMS problems configuring 16xTesla Modules

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New member
May 24, 2022
Hi Everyone,

I'm currently building a off grid solar system that uses 16x Tesla Model S battery modules as storage but facing some issues with configuring the simpBMS so was wondering if anyone could help. The setup is =~ 48 V and uses 3x Victron Quattro connected to provide 3 Phase AC, I keep having issues configuring the correct settings on the battery menu:

The following are my current settings:

1 - Cell Over Voltage Setpoint: 4200mV
2 - Cell Under Voltage Setpoint: 3000mV
3 - Over Temperature Setpoint: 65.00C
4 - Under Temperature Setpoint: -10.00C
5 - Cell Balance Voltage Setpoint: 3900mV
6 - Balance Voltage Hystersis: 40mV
7 - Ah Battery Capacity:1856Ah
8 - Pack Max Discharge: 300.00A
9 - Cell Discharge Voltage Limit Setpoint: 3200mV
0 - Slave strings in parallel: 8
a - Cells in Series per String: 12

b - setpoint 1: 3100mV
c - SOC setpoint 1:10%
d - setpoint 2: 4100mV
e - SOC setpoint 2: 90%
g - Storage Setpoint: 3800mV
h - Discharge Current Taper Offset: 300mV
j - Discharge Current Temperature Derate : 40.00C
k - Cell Discharge Voltage Hysteresis: 200mV

I calculated that for my pack I should have 1856Ah for 48V but not sure what values it expects for slave strings and cells in series?

And the following the result I get:

Module #1 21.58V Cell0: 3.60V Cell1: 3.60V Cell2: 3.60V Cell3: 3.60V Cell4: 3.60V Cell5: 3.60V Neg Term Temp: 16.20C Pos Term Temp: 15.86C
Module #2 21.58V Cell6: 3.59V Cell7: 3.60V Cell8: 3.60V Cell9: 3.60V Cell10: 3.60V Cell11: 3.60V Neg Term Temp: 16.29C Pos Term Temp: 15.91C
Module #3 21.59V Cell12: 3.60V Cell13: 3.60V Cell14: 3.60V Cell15: 3.60V Cell16: 3.60V Cell17: 3.60V Neg Term Temp: 16.53C Pos Term Temp: 15.97C
Module #4 21.57V Cell18: 3.59V Cell19: 3.60V Cell20: 3.60V Cell21: 3.60V Cell22: 3.60V Cell23: 3.59V Neg Term Temp: 16.29C Pos Term Temp: 16.06C
Module #5 21.58V Cell24: 3.59V Cell25: 3.60V Cell26: 3.60V Cell27: 3.60V Cell28: 3.60V Cell29: 3.60V Neg Term Temp: 16.56C Pos Term Temp: 16.00C
Module #6 21.58V Cell30: 3.59V Cell31: 3.60V Cell32: 3.60V Cell33: 3.60V Cell34: 3.60V Cell35: 3.60V Neg Term Temp: 16.42C Pos Term Temp: 16.08C
Module #7 21.60V Cell36: 3.60V Cell37: 3.60V Cell38: 3.60V Cell39: 3.60V Cell40: 3.60V Cell41: 3.60V Neg Term Temp: 16.36C Pos Term Temp: 16.35C
Module #8 21.56V Cell42: 3.59V Cell43: 3.59V Cell44: 3.59V Cell45: 3.59V Cell46: 3.59V Cell47: 3.59V Neg Term Temp: 16.62C Pos Term Temp: 16.20C
Module #9 21.58V Cell48: 3.60V Cell49: 3.60V Cell50: 3.60V Cell51: 3.60V Cell52: 3.60V Cell53: 3.60V Neg Term Temp: 16.38C Pos Term Temp: 16.19C
Module #10 21.58V Cell54: 3.59V Cell55: 3.60V Cell56: 3.60V Cell57: 3.60V Cell58: 3.60V Cell59: 3.60V Neg Term Temp: 16.73C Pos Term Temp: 16.11C
Module #11 21.59V Cell60: 3.60V Cell61: 3.60V Cell62: 3.60V Cell63: 3.60V Cell64: 3.60V Cell65: 3.60V Neg Term Temp: 16.57C Pos Term Temp: 16.37C
Module #12 21.57V Cell66: 3.59V Cell67: 3.60V Cell68: 3.60V Cell69: 3.60V Cell70: 3.60V Cell71: 3.59V Neg Term Temp: 16.84C Pos Term Temp: 16.18C
Module #13 21.57V Cell72: 3.59V Cell73: 3.60V Cell74: 3.60V Cell75: 3.60V Cell76: 3.59V Cell77: 3.59V Neg Term Temp: 16.49C Pos Term Temp: 16.32C
Module #14 21.58V Cell78: 3.59V Cell79: 3.60V Cell80: 3.60V Cell81: 3.60V Cell82: 3.60V Cell83: 3.60V Neg Term Temp: 16.91C Pos Term Temp: 16.44C
Module #15 21.60V Cell84: 3.60V Cell85: 3.60V Cell86: 3.60V Cell87: 3.60V Cell88: 3.60V Cell89: 3.60V Neg Term Temp: 17.23C Pos Term Temp: 16.93C
Module #16 18.82V Cell90: 3.59V Cell91: 3.59V Cell92: 3.59V Cell93: 3.59V Cell94: 3.59V Cell95: 3.59V Neg Term Temp: 17.36C Pos Term Temp: 17.02C
CANbus 0.00mA 47% SOC 6978560.00mAh

Another topic that is not clear is the use of a positive and negative contactor in ESS mode? On the manual seems to indicate only the main contactor is in use ?