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Original question:
Is the bQ34z100-G1 equipped to accurately estimate health of a multi-cell pack?
will other TI fuel gauges that monitor and track impededence/Qmax at a cell level handle individual cell degradation better?
Hello Reed,
The BQ34Z100 is a top of stack gauge so it only measures the health of the full stack. Generally it is limited to the weakest cell, but you will have no visibility into which cell is the weakest like on the BQ40Z50 which has individual cell measurement. The gauge itself is still accurate for higher cell counts.
Sincerely,
Wyatt Keller
Can you please describe the mechanism through which the health tracks the weakest cell? Is this through impedence tracking lowering available capacity? IE, the weakest cell internal resistance will climb significantly as its SOC approaches zero, and the BQ will detect this through RA table update? Please describe the mechanism to help me debug why this is not happening. Thank you.
For reference, here are our settings.
| * Texas Instruments Data Flash File | ||||
| * File created Mon Sep 18 11:55:03 2023 | ||||
| * | ||||
| * Device Number is not available. | ||||
| * Firmware Version is not available. | ||||
| * Build Number is not available. | ||||
| * Order Number not available. | ||||
| * | ||||
| * bqz Device Number 100 | ||||
| * bqz Firmware Version 0.16 | ||||
| * bqz Build Number 17 | ||||
| * | ||||
| * Field Order: Class name | Subclass name | Parameter name | Parameter Value | Display Units |
| Configuration | Safety | OT Chg | 55 | 1degC |
| Configuration | Safety | OT Chg Time | 2 | Seconds |
| Configuration | Safety | OT Chg Recovery | 50 | 1degC |
| Configuration | Safety | OT Dsg | 60 | 1degC |
| Configuration | Safety | OT Dsg Time | 2 | Seconds |
| Configuration | Safety | OT Dsg Recovery | 55 | 1degC |
| Configuration | Charge Inhibit Cfg | Chg Inhibit Temp Low | 0 | 1degC |
| Configuration | Charge Inhibit Cfg | Chg Inhibit Temp High | 45 | 1degC |
| Configuration | Charge Inhibit Cfg | Temp Hys | 5 | 1degC |
| Configuration | Charge | Suspend Low Temp | -5 | 1degC |
| Configuration | Charge | Suspend High Temp | 55 | 1degC |
| Configuration | Charge | Pb Temp Comp | 24.96 | % |
| Configuration | Charge | Pb Reduction Rate | 10 | % |
| Configuration | Charge Termination | Taper Current | 28 | mAmp |
| Configuration | Charge Termination | Min Taper Capacity | 3 | mAmpHr |
| Configuration | Charge Termination | Cell Taper Voltage | 100 | mVolt |
| Configuration | Charge Termination | Current Taper Window | 40 | Seconds |
| Configuration | Charge Termination | TCA Set % | 99 | Percent |
| Configuration | Charge Termination | TCA Clear % | 95 | Percent |
| Configuration | Charge Termination | FC Set % | 100 | Percent |
| Configuration | Charge Termination | FC Clear % | 98 | Percent |
| Configuration | Charge Termination | DODatEOC Delta T | 10 | 1degC |
| Configuration | Charge Termination | NiMH Delta Temp | 3 | 1degC |
| Configuration | Charge Termination | NiMH Delta Temp Time | 180 | Seconds |
| Configuration | Charge Termination | NiMH Hold Off Time | 100 | Seconds |
| Configuration | Charge Termination | NiMH Hold Off Current | 240 | mAmp |
| Configuration | Charge Termination | NiMH Hold Off Temp | 25 | 1degC |
| Configuration | Charge Termination | NiMH Cell Negative Delta Volt | 17 | mVolt |
| Configuration | Charge Termination | NiMH Cell Negative Delta Time | 16 | Seconds |
| Configuration | Charge Termination | NiMH Cell Neg Delta Qual Volt | 4200 | mVolt |
| Configuration | Data | Manuf Date | ######## | Day + Mo*32 + (Yr -1980)*256 |
| Configuration | Data | Ser. Num. | 002d | hex |
| Configuration | Data | Cycle Count | 31 | Count |
| Configuration | Data | CC Threshold | 1000 | mAmpHr |
| Configuration | Data | Max Error Limit | 100 | % |
| Configuration | Data | Design Capacity | 1272 | MilliAmpHour |
| Configuration | Data | Design Energy | 4815 | MilliWattHour |
| Configuration | Data | SOH Load I | -2888 | MilliAmp |
| Configuration | Data | Cell Charge Voltage T1-T2 | 4300 | mV |
| Configuration | Data | Cell Charge Voltage T2-T3 | 4300 | mV |
| Configuration | Data | Cell Charge Voltage T3-T4 | 4300 | mV |
| Configuration | Data | Charge Current T1-T2 | 10 | Percent |
| Configuration | Data | Charge Current T2-T3 | 50 | Percent |
| Configuration | Data | Charge Current T3-T4 | 30 | Percent |
| Configuration | Data | JEITA T1 | 0 | degC |
| Configuration | Data | JEITA T2 | 10 | degC |
| Configuration | Data | JEITA T3 | 45 | degC |
| Configuration | Data | JEITA T4 | 55 | degC |
| Configuration | Data | Design Energy Scale | 9 | Number |
| Configuration | Data | Device Name | SB Rogue1 | - |
| Configuration | Data | Manufacturer Name | Texas Inst. | - |
| Configuration | Data | Device Chemistry | LION | - |
| Configuration | Discharge | SOC1 Set Threshold | 150 | mAh |
| Configuration | Discharge | SOC1 Clear Threshold | 175 | mAh |
| Configuration | Discharge | SOCF Set Threshold | 75 | mAh |
| Configuration | Discharge | SOCF Clear Threshold | 100 | mAh |
| Configuration | Discharge | Cell BL Set Volt Threshold | 2800 | mVolt |
| Configuration | Discharge | Cell BL Set Volt Time | 2 | Seconds |
| Configuration | Discharge | Cell BL Clear Volt Threshold | 2900 | mVolt |
| Configuration | Discharge | Cell BH Set Volt Threshold | 4400 | mVolt |
| Configuration | Discharge | Cell BH Volt Time | 2 | Seconds |
| Configuration | Discharge | Cell BH Clear Volt Threshold | 4350 | mVolt |
| Configuration | Discharge | Cycle Delta | 0.05 | % |
| Configuration | Manufacturer Data | Pack Lot Code | 0 | hex |
| Configuration | Manufacturer Data | PCB Lot Code | 0 | hex |
| Configuration | Manufacturer Data | Firmware Version | 0 | hex |
| Configuration | Manufacturer Data | Hardware Revision | 0 | hex |
| Configuration | Manufacturer Data | Cell Revision | 0 | hex |
| Configuration | Manufacturer Data | DF Config Version | 0 | hex |
| Configuration | Integrity Data | Static Chem DF Checksum | 743c | Number |
| Configuration | Lifetime Data | Lifetime Max Temp | 57.5 | 1degC |
| Configuration | Lifetime Data | Lifetime Min Temp | 19.8 | 1degC |
| Configuration | Lifetime Data | Lifetime Max Chg Current | 1380 | mAmp |
| Configuration | Lifetime Data | Lifetime Max Dsg Current | -3418 | mA |
| Configuration | Lifetime Data | Lifetime Max Pack Voltage | 1290 | 20mV |
| Configuration | Lifetime Data | Lifetime Min Pack Voltage | 980 | 20mV |
| Configuration | Lifetime Temp Samples | LT Flash Cnt | 30 | Count |
| Configuration | Registers | Pack Configuration | 29c1 | flags |
| Configuration | Registers | Pack Configuration B | af | flags |
| Configuration | Registers | Pack Configuration C | 37 | flags |
| Configuration | Registers | LED_Comm Configuration | 0 | flags |
| Configuration | Registers | Alert Configuration | 0 | flags |
| Configuration | Registers | Number of series cell | 6 | num |
| Configuration | Lifetime Resolution | LT Temp Res | 1 | 1degC |
| Configuration | Lifetime Resolution | LT Cur Res | 100 | mA |
| Configuration | Lifetime Resolution | LT V Res | 1 | 20mV |
| Configuration | Lifetime Resolution | LT Update Time | 60 | Seconds |
| Configuration | LED Display | LED Hold Time | 4 | Num |
| Configuration | Power | Flash Update OK Cell Volt | 2800 | mVolt |
| Configuration | Power | Sleep Current | 10 | mAmp |
| Configuration | Power | FS Wait | 5 | Seconds |
| System Data | Manufacturer Info | Block A 0 | 0 | hex |
| System Data | Manufacturer Info | Block A 1 | 0 | hex |
| System Data | Manufacturer Info | Block A 2 | 0 | hex |
| System Data | Manufacturer Info | Block A 3 | 0 | hex |
| System Data | Manufacturer Info | Block A 4 | 0 | hex |
| System Data | Manufacturer Info | Block A 5 | 0 | hex |
| System Data | Manufacturer Info | Block A 6 | 0 | hex |
| System Data | Manufacturer Info | Block A 7 | 0 | hex |
| System Data | Manufacturer Info | Block A 8 | 0 | hex |
| System Data | Manufacturer Info | Block A 9 | 0 | hex |
| System Data | Manufacturer Info | Block A 10 | 0 | hex |
| System Data | Manufacturer Info | Block A 11 | 0 | hex |
| System Data | Manufacturer Info | Block A 12 | 0 | hex |
| System Data | Manufacturer Info | Block A 13 | 0 | hex |
| System Data | Manufacturer Info | Block A 14 | 0 | hex |
| System Data | Manufacturer Info | Block A 15 | 0 | hex |
| System Data | Manufacturer Info | Block A 16 | 0 | hex |
| System Data | Manufacturer Info | Block A 17 | 0 | hex |
| System Data | Manufacturer Info | Block A 18 | 0 | hex |
| System Data | Manufacturer Info | Block A 19 | 0 | hex |
| System Data | Manufacturer Info | Block A 20 | 0 | hex |
| System Data | Manufacturer Info | Block A 21 | 0 | hex |
| System Data | Manufacturer Info | Block A 22 | 0 | hex |
| System Data | Manufacturer Info | Block A 23 | 0 | hex |
| System Data | Manufacturer Info | Block A 24 | 0 | hex |
| System Data | Manufacturer Info | Block A 25 | 0 | hex |
| System Data | Manufacturer Info | Block A 26 | 0 | hex |
| System Data | Manufacturer Info | Block A 27 | 0 | hex |
| System Data | Manufacturer Info | Block A 28 | 0 | hex |
| System Data | Manufacturer Info | Block A 29 | 0 | hex |
| System Data | Manufacturer Info | Block A 30 | 0 | hex |
| System Data | Manufacturer Info | Block A 31 | 0 | hex |
| Gas Gauging | IT Cfg | Load Select | 6 | Number |
| Gas Gauging | IT Cfg | Load Mode | 1 | Number |
| Gas Gauging | IT Cfg | Max Res Factor | 15 | num |
| Gas Gauging | IT Cfg | Min Res Factor | 1 | num |
| Gas Gauging | IT Cfg | Ra Filter | 800 | num |
| Gas Gauging | IT Cfg | Min PassedChg NiMH-LA 1st Qmax | 50 | % |
| Gas Gauging | IT Cfg | Maximum Qmax Change | 30 | % |
| Gas Gauging | IT Cfg | Cell Terminate Voltage | 3500 | mVolt |
| Gas Gauging | IT Cfg | Cell Term V Delta | 200 | mVolt |
| Gas Gauging | IT Cfg | ResRelax Time | 500 | Seconds |
| Gas Gauging | IT Cfg | User Rate-mA | 0 | MilliAmp |
| Gas Gauging | IT Cfg | User Rate-Pwr | 6778 | mW/cW |
| Gas Gauging | IT Cfg | Reserve Cap-mAh | 0 | MilliAmpHour |
| Gas Gauging | IT Cfg | Reserve Energy | 0 | mWh/cWh |
| Gas Gauging | IT Cfg | Max Scale Back Grid | 4 | num |
| Gas Gauging | IT Cfg | Cell Min DeltaV | 0 | mVolt |
| Gas Gauging | IT Cfg | Ra Max Delta | 15 | % |
| Gas Gauging | IT Cfg | Design Resistance | 52 | mOhms |
| Gas Gauging | IT Cfg | Reference Grid | 4 | - |
| Gas Gauging | IT Cfg | Qmax Max Delta % | 10 | mAmpHour |
| Gas Gauging | IT Cfg | Max Res Scale | 5000 | Num |
| Gas Gauging | IT Cfg | Min Res Scale | 200 | Num |
| Gas Gauging | IT Cfg | Fast Scale Start SOC | 10 | % |
| Gas Gauging | IT Cfg | Charge Hys V Shift | 40 | mVolt |
| Gas Gauging | IT Cfg | Smooth Relax Time | 1000 | s |
| Gas Gauging | Current Thresholds | Dsg Current Threshold | 7 | mAmp |
| Gas Gauging | Current Thresholds | Chg Current Threshold | 7 | mAmp |
| Gas Gauging | Current Thresholds | Quit Current | 5 | mAmp |
| Gas Gauging | Current Thresholds | Dsg Relax Time | 60 | Seconds |
| Gas Gauging | Current Thresholds | Chg Relax Time | 60 | Seconds |
| Gas Gauging | Current Thresholds | Cell Max IR Correct | 400 | mV |
| Gas Gauging | State | Qmax Cell 0 | 1252 | mAmpHr |
| Gas Gauging | State | Cycle Count | 31 | num |
| Gas Gauging | State | Update Status | 6 | num |
| Gas Gauging | State | Cell V at Chg Term | 4298 | mVolt |
| Gas Gauging | State | Avg I Last Run | -2999 | mAmp |
| Gas Gauging | State | Avg P Last Run | -1263 | MilliWattHour |
| Gas Gauging | State | Cell Delta Voltage | 7 | mVolt |
| Gas Gauging | State | T Rise | 20 | Num |
| Gas Gauging | State | T Time Constant | 1000 | Num |
| Ra Table | R_a0 | R_a0 Flag | 0 | Hex |
| Ra Table | R_a0 | R_a0 0 | 44 | Num |
| Ra Table | R_a0 | R_a0 1 | 47 | Num |
| Ra Table | R_a0 | R_a0 2 | 56 | Num |
| Ra Table | R_a0 | R_a0 3 | 78 | Num |
| Ra Table | R_a0 | R_a0 4 | 48 | Num |
| Ra Table | R_a0 | R_a0 5 | 38 | Num |
| Ra Table | R_a0 | R_a0 6 | 42 | Num |
| Ra Table | R_a0 | R_a0 7 | 80 | Num |
| Ra Table | R_a0 | R_a0 8 | 80 | Num |
| Ra Table | R_a0 | R_a0 9 | 80 | Num |
| Ra Table | R_a0 | R_a0 10 | 80 | Num |
| Ra Table | R_a0 | R_a0 11 | 2 | Num |
| Ra Table | R_a0 | R_a0 12 | 1 | Num |
| Ra Table | R_a0 | R_a0 13 | 2 | Num |
| Ra Table | R_a0 | R_a0 14 | 0 | Num |
| Ra Table | R_a0x | R_a0x Flag | 55 | Hex |
| Ra Table | R_a0x | R_a0x 0 | 44 | Num |
| Ra Table | R_a0x | R_a0x 1 | 47 | Num |
| Ra Table | R_a0x | R_a0x 2 | 56 | Num |
| Ra Table | R_a0x | R_a0x 3 | 78 | Num |
| Ra Table | R_a0x | R_a0x 4 | 48 | Num |
| Ra Table | R_a0x | R_a0x 5 | 38 | Num |
| Ra Table | R_a0x | R_a0x 6 | 42 | Num |
| Ra Table | R_a0x | R_a0x 7 | 88 | Num |
| Ra Table | R_a0x | R_a0x 8 | 88 | Num |
| Ra Table | R_a0x | R_a0x 9 | 88 | Num |
| Ra Table | R_a0x | R_a0x 10 | 88 | Num |
| Ra Table | R_a0x | R_a0x 11 | 2 | Num |
| Ra Table | R_a0x | R_a0x 12 | 1 | Num |
| Ra Table | R_a0x | R_a0x 13 | 2 | Num |
| Ra Table | R_a0x | R_a0x 14 | 0 | Num |
| Calibration | Data | CC Gain | 4.616 | mohm |
| Calibration | Data | CC Delta | 4.607 | mohm |
| Calibration | Data | CC Offset | -1316 | num |
| Calibration | Data | Board Offset | -13 | num |
| Calibration | Data | Int Temp Offset | 0 | degC |
| Calibration | Data | Ext Temp Offset | 0 | degC |
| Calibration | Data | Voltage Divider | 29877 | mVolt |
| Calibration | Current | Deadband | 5 | mAmp |
| Security | Codes | Sealed to Unsealed | 0 | hex |
| Security | Codes | Unsealed to Full | 0 | hex |
| Security | Codes | Authen Key3 | 0 | hex |
| Security | Codes | Authen Key2 | 0 | hex |
| Security | Codes | Authen Key1 | 0 | hex |
| Security | Codes | Authen Key0 | 0 | hex |
Hello Reed,
Yes, please reference our documentation on the operation principles of impedance track: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1100653/faq-impedance-track-faqs
The weakest cell of the stack will always limit the total stack capability because of the Qmax and Increased resistance.
Sincerely,
Wyatt Keller
