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BQ34Z100-G1: Inadequate values of Battery Gauge capacity estimates

Jeff Lam55
Intellectual 420 points
Part Number: BQ34Z100-G1

Hi, 

We launched a product two years ago that uses BQ34Z100-G1 mainly to monitor our internal battery level (1S2P 1200mAh, Lithium-ion). The gauge was calibrated and a golden image was generated by TI FAE team in Taiwan.

We recently observed an uptake from customers reprorting that battery level isn't accurate.

From our investigation, the values of battery gauge registers:

RemainingCapacity() - RM - 0x04/0x05
FullChargeCapacity() - FCC - 0x06/0x07
TrueRC() - TRC - 0x68/0x69
TrueFCC() - TFCC - 0x6A/0x6B

are often do not behave adequately during the process of charging and discharging (and especially repeated partial charging or discharging).

-- In the process of repeated charging/discharging cycles (possibly partial) FullChargeCapacity() sometimes happen to get weird values like 600mAh or even 100-300mAh. FCC value may recover to expected value sometime after a few cycles of discharging/charging . We observed values of FullChargeCapacity() as small as 74mAh and on one device even 0mAh (even though battery doesn't seem to be at fault). 

So in short: FullChargeCapacity() sometimes happen to be random and unpredictable with no clear explanation how it happened. 

Please let me know if you have any idea what could lead to this problem and if you have any recommendation for actions we could take. Thank you!

I've exported Data flash file (.csv format) in included in here. I added a column so you can compare the values between a new unit and an old unit. 

* Texas Instruments Data Flash File
* Values of a new unit Values of an old unit
* Field Order: Class name  Subclass name  Parameter name  Parameter Value  Parameter Value  Display Units
Configuration Safety OT Chg 55 55 1degC
Configuration Safety OT Chg Time 2 2 Seconds
Configuration Safety OT Chg Recovery 50 50 1degC
Configuration Safety OT Dsg 60 60 1degC
Configuration Safety OT Dsg Time 2 2 Seconds
Configuration Safety OT Dsg Recovery 55 55 1degC
Configuration Charge Inhibit Cfg Chg Inhibit Temp Low 0 0 1degC
Configuration Charge Inhibit Cfg Chg Inhibit Temp High 45 45 1degC
Configuration Charge Inhibit Cfg Temp Hys 5 5 1degC
Configuration Charge Suspend Low Temp -5 -5 1degC
Configuration Charge Suspend High Temp 55 55 1degC
Configuration Charge Pb EFF Efficiency 100 100 %
Configuration Charge Pb Temp Comp 24.96 24.96 %
Configuration Charge Pb Drop Off Percent 96 96 %
Configuration Charge Pb Reduction Rate 10 10 %
Configuration Charge Termination Taper Current 296 296 mAmp
Configuration Charge Termination Min Taper Capacity 240 240 mAmpHr
Configuration Charge Termination Cell Taper Voltage 100 100 mVolt
Configuration Charge Termination Current Taper Window 40 40 Seconds
Configuration Charge Termination TCA Set % 99 99 Percent
Configuration Charge Termination TCA Clear % 95 95 Percent
Configuration Charge Termination FC Set % -1 -1 Percent
Configuration Charge Termination FC Clear % 98 98 Percent
Configuration Charge Termination DODatEOC Delta T 10 10 1degC
Configuration Charge Termination NiMH Delta Temp 3 3 1degC
Configuration Charge Termination NiMH Delta Temp Time 180 180 Seconds
Configuration Charge Termination NiMH Hold Off  Time 100 100 Seconds
Configuration Charge Termination NiMH Hold Off Current 240 240 mAmp
Configuration Charge Termination NiMH Hold Off  Temp 25 25 1degC
Configuration Charge Termination NiMH Cell Negative Delta Volt 17 17 mVolt
Configuration Charge Termination NiMH Cell Negative Delta Time 16 16 Seconds
Configuration Charge Termination NiMH Cell Neg Delta Qual Volt 4200 4200 mVolt
Configuration Data Manufacture Date 1/1/1980 1/1/1980 Day + Mo*32 + (Yr -1980)*256
Configuration Data Serial Number 1 1 hex
Configuration Data Cycle Count 0 5 Count
Configuration Data CC Threshold 960 960 mAmpHr
Configuration Data Max Error Limit 100 100 %
Configuration Data Design Capacity 1160 1160 MilliAmpHour
Configuration Data Design Energy 4440 4440 MilliWattHour
Configuration Data SOH Load I -400 -400 MilliAmp
Configuration Data Cell Charge Voltage T1-T2 4200 4200 mV
Configuration Data Cell Charge Voltage T2-T3 4200 4200 mV
Configuration Data Cell Charge Voltage T3-T4 4200 4200 mV
Configuration Data Charge Current T1-T2 10 10 Percent
Configuration Data Charge Current  T2-T3 50 50 Percent
Configuration Data Charge Current  T3-T4 30 30 Percent
Configuration Data JEITA T1 0 0 degC
Configuration Data JEITA T2 10 10 degC
Configuration Data JEITA T3 45 45 degC
Configuration Data JEITA T4 55 55 degC
Configuration Data Design Energy Scale 1 1 Number
Configuration Data Device Name bq34z100-G1 bq34z100-G1 -
Configuration Data Manufacturer Name Texas Inst. Texas Inst. -
Configuration Data Device Chemistry LION LION -
Configuration Discharge SOC1 Set Threshold 174 174 mAh
Configuration Discharge SOC1 Clear Threshold 203 203 mAh
Configuration Discharge SOCF Set Threshold 87 87 mAh
Configuration Discharge SOCF Clear Threshold 116 116 mAh
Configuration Discharge Cell BL Set Volt Threshold 3000 3000 mVolt
Configuration Discharge Cell BL Set Volt Time 2 2 Seconds
Configuration Discharge Cell BL Clear Volt Threshold 3200 3200 mVolt
Configuration Discharge Cell BH Set Volt Threshold 4200 4200 mVolt
Configuration Discharge Cell BH Volt Time 2 2 Seconds
Configuration Discharge Cell BH  Clear Volt Threshold 4200 4200 mVolt
Configuration Discharge Cycle Delta 0.05 0.05 %
Configuration Manufacturer Data Pack Lot Code 0 0 hex
Configuration Manufacturer Data PCB Lot Code 0 0 hex
Configuration Manufacturer Data Firmware Version 0 0 hex
Configuration Manufacturer Data Hardware Revision 0 0 hex
Configuration Manufacturer Data Cell Revision 0 0 hex
Configuration Manufacturer Data DF Config Version 0 0 hex
Configuration Lifetime Data Lifetime Max Temp 30 79 1degC
Configuration Lifetime Data Lifetime Min Temp 20 -13.9 1degC
Configuration Lifetime Data Lifetime Max Chg Current 1291 1865 mAmp
Configuration Lifetime Data Lifetime Max Dsg Current -1884 -1884 mA
Configuration Lifetime Data Lifetime Max Pack Voltage 210 210 20mV
Configuration Lifetime Data Lifetime Min Pack Voltage 151 149 20mV
Configuration Lifetime Temp Samples LT Flash Cnt 12 66 Count
Configuration Registers Pack Configuration 1.00E+01 1.00E+01 flags
Configuration Registers Pack Configuration B a1 a1 flags
Configuration Registers Pack Configuration C 33 33 flags
Configuration Registers LED_Comm Configuration 0a 0a flags
Configuration Registers Alert Configuration 0 0 flags
Configuration Registers Number of series cell 1 1 num
Configuration Lifetime Resolution LT Temp Res 1 1 1degC
Configuration Lifetime Resolution LT Cur Res 100 100 mA
Configuration Lifetime Resolution LT V Res 1 1 20mV
Configuration Lifetime Resolution LT Update Time 60 60 Seconds
Configuration LED Display LED Hold Time 4 4 Num
Configuration Power Flash Update OK Cell Volt 2800 2800 mVolt
Configuration Power Sleep Current 10 10 mAmp
Configuration Power FS Wait 10 10 Seconds
System Data Manufacturer Info Block A 0 20 20 hex
System Data Manufacturer Info Block A 1 16 16 hex
System Data Manufacturer Info Block A 2 7 7 hex
System Data Manufacturer Info Block A 3 26 26 hex
System Data Manufacturer Info Block A 4 0 0 hex
System Data Manufacturer Info Block A 5 1 1 hex
System Data Manufacturer Info Block A 6 0 0 hex
System Data Manufacturer Info Block A 7 0 0 hex
System Data Manufacturer Info Block A 8 0 0 hex
System Data Manufacturer Info Block A 9 0 0 hex
System Data Manufacturer Info Block A 10 0 0 hex
System Data Manufacturer Info Block A 11 0 0 hex
System Data Manufacturer Info Block A 12 0 0 hex
System Data Manufacturer Info Block A 13 0 0 hex
System Data Manufacturer Info Block A 14 0 0 hex
System Data Manufacturer Info Block A 15 0 0 hex
System Data Manufacturer Info Block A 16 0 0 hex
System Data Manufacturer Info Block A 17 0 0 hex
System Data Manufacturer Info Block A 18 0 0 hex
System Data Manufacturer Info Block A 19 0 0 hex
System Data Manufacturer Info Block A 20 0 0 hex
System Data Manufacturer Info Block A 21 0 0 hex
System Data Manufacturer Info Block A 22 0 0 hex
System Data Manufacturer Info Block A 23 0 0 hex
System Data Manufacturer Info Block A 24 0 0 hex
System Data Manufacturer Info Block A 25 0 0 hex
System Data Manufacturer Info Block A 26 0 0 hex
System Data Manufacturer Info Block A 27 0 0 hex
System Data Manufacturer Info Block A 28 0 0 hex
System Data Manufacturer Info Block A 29 0 0 hex
System Data Manufacturer Info Block A 30 0 0 hex
System Data Manufacturer Info Block A 31 0 0 hex
Gas Gauging IT Cfg Load Select 2 2 Number
Gas Gauging IT Cfg Load Mode 1 1 Number
Gas Gauging IT Cfg Res Current 10 10 mAmp
Gas Gauging IT Cfg Max Res Factor 50 50 num
Gas Gauging IT Cfg Min Res Factor 1 1 num
Gas Gauging IT Cfg Ra Filter 500 500 num
Gas Gauging IT Cfg Min PassedChg NiMH-LA 1st Qmax 50 50 %
Gas Gauging IT Cfg Maximum Qmax Change 100 100 %
Gas Gauging IT Cfg Cell Terminate Voltage 3200 3200 mVolt
Gas Gauging IT Cfg Cell Term V Delta 200 200 mVolt
Gas Gauging IT Cfg ResRelax Time 500 500 Seconds
Gas Gauging IT Cfg User Rate-mA 0 0 MilliAmp
Gas Gauging IT Cfg User Rate-Pwr 0 0 mW/cW
Gas Gauging IT Cfg Reserve Cap-mAh 0 0 MilliAmpHour
Gas Gauging IT Cfg Reserve Energy 0 0 mWh/cWh
Gas Gauging IT Cfg Max Scale Back Grid 4 4 num
Gas Gauging IT Cfg Cell Min DeltaV 0 0 mVolt
Gas Gauging IT Cfg Ra Max Delta 15 15 %
Gas Gauging IT Cfg Design Resistance 173 173 mOhms
Gas Gauging IT Cfg Reference Grid 4 4 -
Gas Gauging IT Cfg Qmax Max Delta % 10 10 mAmpHour
Gas Gauging IT Cfg Max Res Scale 32000 32000 Num
Gas Gauging IT Cfg Min Res Scale 1 1 Num
Gas Gauging IT Cfg Fast Scale Start SOC 10 10 %
Gas Gauging IT Cfg Charge Hys V Shift 40 40 mVolt
Gas Gauging IT Cfg Smooth Relax Time 1000 1000 s
Gas Gauging Current Thresholds Dsg Current Threshold 60 60 mAmp
Gas Gauging Current Thresholds Chg Current Threshold 75 75 mAmp
Gas Gauging Current Thresholds Quit Current 40 40 mAmp
Gas Gauging Current Thresholds Dsg Relax Time 60 60 Seconds
Gas Gauging Current Thresholds Chg Relax Time 60 60 Seconds
Gas Gauging Current Thresholds Cell Max IR Correct 400 400 mV
Gas Gauging State Qmax Cell 0 1171 1174 mAmpHr
Gas Gauging State Cycle Count 0 0 num
Gas Gauging State Update Status 6 6 num
Gas Gauging State Cell V at Chg Term 4187 4158 mVolt
Gas Gauging State Avg I Last Run -239 -779 mAmp
Gas Gauging State Avg P Last Run -906 -2944 MilliWattHour
Gas Gauging State Cell Delta Voltage 1 8 mVolt
Gas Gauging State T Rise 20 20 Num
Gas Gauging State T Time Constant 1000 1000 Num
Ra Tables Ra0 Table Ra Flag 55 0 Hex
Ra Tables Ra0 Table Ra 0 56 46 Num
Ra Tables Ra0 Table Ra 1 56 46 Num
Ra Tables Ra0 Table Ra 2 176 153 Num
Ra Tables Ra0 Table Ra 3 227 283 Num
Ra Tables Ra0 Table Ra 4 173 429 Num
Ra Tables Ra0 Table Ra 5 181 552 Num
Ra Tables Ra0 Table Ra 6 235 840 Num
Ra Tables Ra0 Table Ra 7 218 772 Num
Ra Tables Ra0 Table Ra 8 218 772 Num
Ra Tables Ra0 Table Ra 9 217 772 Num
Ra Tables Ra0 Table Ra 10 193 714 Num
Ra Tables Ra0 Table Ra 11 233 840 Num
Ra Tables Ra0 Table Ra 12 285 1041 Num
Ra Tables Ra0 Table Ra 13 349 1242 Num
Ra Tables Ra0 Table Ra 14 3438 12400 Num
Ra Tables Ra0x Table Ra Flag 0 55 Hex
Ra Tables Ra0x Table Ra 0 56 46 Num
Ra Tables Ra0x Table Ra 1 56 46 Num
Ra Tables Ra0x Table Ra 2 176 153 Num
Ra Tables Ra0x Table Ra 3 227 309 Num
Ra Tables Ra0x Table Ra 4 173 468 Num
Ra Tables Ra0x Table Ra 5 181 603 Num
Ra Tables Ra0x Table Ra 6 235 917 Num
Ra Tables Ra0x Table Ra 7 218 843 Num
Ra Tables Ra0x Table Ra 8 218 843 Num
Ra Tables Ra0x Table Ra 9 217 843 Num
Ra Tables Ra0x Table Ra 10 193 780 Num
Ra Tables Ra0x Table Ra 11 233 917 Num
Ra Tables Ra0x Table Ra 12 285 1137 Num
Ra Tables Ra0x Table Ra 13 364 1356 Num
Ra Tables Ra0x Table Ra 14 3586 13539 Num
Calibration Data CC Gain 10.748 10.748 mohm
Calibration Data CC Delta 10.73 10.73 mohm
Calibration Data CC Offset -1273 -1274 num
Calibration Data Board Offset 14 14 num
Calibration Data Int Temp Offset 0 0 degC
Calibration Data Ext Temp Offset 0 0 degC
Calibration Data Voltage Divider 5004 5004 mVolt
Calibration Current Deadband 5 5 mAmp
Security Codes Sealed to Unsealed 36720414 36720414 hex
Security Codes Unsealed to Full ffffffff ffffffff hex
Security Codes Authen Key3 1234567 1234567 hex
Security Codes Authen Key2 89abcdef 89abcdef hex
Security Codes Authen Key1 fedcba98 fedcba98 hex
Security Codes Authen Key0 76543210 76543210 hex

   

  • 0
    TI__Genius 14985 points
    Hi Jeff,

    It looks like Qmax never had the opportunity to learn. This can cause the Ra table to learn incorrectly and then gauging accuracy will definitely be impacted.
    Can you please run an "unfiltered" learning cycle on some of the aged packs and see what Qmax and Ra should be?
    Discharge to empty, rest at least 5 hours, then set Update Status to 00, Ra Flags = FFFF. Sent the RESET command, then the IT_ENABLE command, then start charging, rest at least two hours (or until Qmax updates), then discharge to empty and rest at least 5 hours (or until Qmax updates again). Then compare the Qmax and Ra values after this cycle with the golden and the as-received values.
  • 0 in reply to dMax
    Intellectual 420 points
    Shouldn't Qmax constantly get updated as the battery get charged and discharged? When you said Qmax never had the opportunity to learn, is this suppose to happen during product production or during normal usage of the battery?

    Thanks,
  • 0 in reply to Jeff Lam55
    TI__Genius 14985 points

    The goal is to update periodically in the field when the Qmax update conditions are met.  For this gauge it requires two relaxed voltage measurements that are separated by at least 37%.  There are some other caveats, so can you share your typical usage profile?  Capacity fades fairly slowly so it doesn't need to get a Qmax update very often, but if years go by and it never updates then that can be a problem.