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BQ20Z80: RSOC jump after charging

Van Nguyen
Prodigy 10 points
Part Number: BQ20Z80
Other Parts Discussed in Thread: GPCCHEM

Hi E2E Members

We have a battery on which we perform maintenance before shipping to manually initialize the impedance track (charging and discharging with appropriate relaxation and waiting times, see graphic). To comply with international transportation regulations, we only charge the Li-ion battery up to 30% RSOC.
We have now found that jumps in the RSOC occur during the relaxation phase at the end of the cycle (yellow marked in graphic). We would like to know why these jumps occur. The charging current is switched off and the temperature dropped by approx. 5°C some time ago. Why does it happen after some time? And it doesn't happen with all batteries. Is it due to the adjustment of the FCC algorithm? 
I hope you can help us determine the root cause.

  • 0
    TI__Guru** 105870 points

    Hello Van,

    Please review our Impedance Track FAQ which has some guides with the information we need in order to help with debug.

    https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1100653/faq-impedance-track-faqs

    FCC is constantly recalculated depending on the load condition and temperature.

    What chem ID is being used now and how was it selected?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 10 points

    Hello Wyatt,

    Our chem ID is ID203. It's a Panasonic cell CGR18650CG. Selection was done over the chemistry selection of bqEasy.

    attached you will also find the gg file.

    I wonder why the jump happens in the middle of the rest period which lasts 2-3 hours. There is no load change and the temperature should be in a stable state.

  • 0 in reply to Van Nguyen
    Prodigy 10 points

    Fullscreen goldenFile.txt Download 
    [Header]
bq EVSW Version = 0.9.79	
DeviceName = bq20z80 v1.10



[Voltage(1st Level Safety)]
COV Threshold = 4300
COV Time = 2
COV Recovery = 3900
COV Delta = 20
COV Temp. Hys = 100
POV Threshold = 17200
POV Time = 2
POV Recovery = 16000
CUV Threshold = 2400
CUV Time = 2
CUV Recovery = 3000
PUV Threshold = 11000
PUV Time = 2
PUV Recovery = 12400
[Current(1st Level Safety)]
OC (1st Tier) Chg = 4000
OC (1st Tier) Chg Time = 5
OC Chg Recovery = 200
OC (1st Tier) Dsg = 9000
OC (1st Tier) Dsg Time = 10
OC Dsg Recovery = 200
OC (2nd Tier) Chg = 4500
OC (2nd Tier) Chg Time = 2
OC (2nd Tier) Dsg = 9500
OC (2nd Tier) Dsg Time = 2
Current Recovery Time = 8
AFE OC Dsg = 0A
AFE OC Dsg Time = 0F
AFE OC Dsg Recovery = 100
AFE SC Chg Cfg = 56
AFE SC Dsg Cfg = 56
AFE SC Recovery = 1
[Temperature(1st Level Safety)]
Over Temp Chg = 500
OT Chg Time = 2
OT Chg Recovery = 450
Over Temp Dsg = 600
OT Dsg Time = 2
OT Dsg Recovery = 550
[Host Comm(1st Level Safety)]
Host Watchdog Timeout = 0

[Voltage(2nd Level Safety)]
SOV Threshold = 18000
SOV Time = 5
Cell Imbalance Current = 5
Cell Imbalance Fail Voltage = 500
Cell Imbalance Time = 30
Battery Rest Time = 1800
PFIN Detect Time = 5
[Current(2nd Level Safety)]
SOC Chg = 11000
SOC Chg Time = 5
SOC Dsg = 11000
SOC Dsg Time = 5
[Temperature(2nd Level Safety)]
SOT Chg = 600
SOT Chg Time = 5
SOT Dsg = 750
SOT Dsg Time = 5
Open Thermistor = -333
Open Time = 5
[FET Verification(2nd Level Safety)]
FET Fail Limit = 20
FET Fail Time = 5
[AFE Verification(2nd Level Safety)]
AFE Check Time = 0
AFE Fail Limit = 10
AFE Fail Recovery Time = 20
AFE Init Retry Limit = 6
AFE Init Limit = 20
[Fuse Verification(2nd Level Safety)]
Fuse Fail Limit = 2
Fuse Fail Time = 0

[Charge Inhibit Cfg(Charge Control)]
Chg Inhibit Temp Low = 0
Chg Inhibit Temp High = 500
Temp Hys = 10
[Pre-Charge Cfg(Charge Control)]
Pre-chg Current = 550
Pre-chg Temp = 120
Pre-chg Voltage = 3000
Recovery Voltage = 3100
[Fast Charge Cfg(Charge Control)]
Fast Charge Current = 3000
Charging Voltage = 16800
Delta Temp = 25
Suspend Low Temp = -50
Suspend High Temp = 500
[Pulse Charge Cfg(Charge Control)]
Turn ON Voltage = 4150
Turn OFF Voltage = 4250
Max ON Pulse Time = 240
Min OFF Pulse Time = 40
Max OFF Voltage = 4270
[Termination Cfg.(Charge Control)]
Maintenance Current = 0
Taper Current = 550
Termination Voltage = 300
Current Taper Window = 40
TCA Set % = -1
TCA Clear % = 95
FC Set % = -1
FC Clear % = 98
[Cell Balancing Cfg(Charge Control)]
Min Cell Deviation = 1750
[Charging Faults(Charge Control)]
Over Charging Voltage = 500
Over Charging Volt Time = 2
Over Charging Current = 500
Over Charging Curr Time = 2
Over Charging Curr Recov = 100
Depleted Voltage = 10000
Depleted Voltage Time = 2
Depleted Recovery = 10500
Over Charge Capacity = 1000
Over Charge Recovery = 2
FC-MTO = 21600
PC-MTO = 3600
Charge Fault Cfg = 3F

[Data(SBS Configuration)]
Rem Cap Alarm = 700
Rem Energy Alarm = 10000
Rem Time Alarm = 10
Init Battery Mode = 8081
Design Voltage = 14400
Spec Info = 0031
Manuf Date = 03-Jul-2013
Ser. Num. = 1
Cycle Count = 0
CC Threshold = 2812
CC % = 25
CF MaxError Limit = 4
Design Capacity = 11250
Design Energy = 16200
Manuf Name = Thoratec
Device Name = bq20z80
Device Chemistry = LION
[Configuration(SBS Configuration)]
TDA Set % = 6
TDA Clear % = 8
FD Set % = -1
FD Clear % = 5
TDA Set Volt Threshold = 13200
TDA Set Volt Time = 5
TDA Clear Volt = 13400
FD Set Volt Threshold = 12000
FD Volt Time = 1
FD Clear Volt = 12400

[Manufacturer Data(System Data)]
Pack Lot Code = 0000
PCB Lot Code = 0000
Firmware Version = 000B
Hardware Revision = 0000
Cell Revision = 0000
[Manufacturer Info(System Data)]
Manuf. Info = 12345678
[Lifetime Data(System Data)]
Lifetime Max Temp = 250
Lifetime Min Temp = 250
Lifetime Max Cell Voltage = 4000
Lifetime Min Cell Voltage = 4000
Lifetime Max Pack Voltage = 16000
Lifetime Min Pack Voltage = 15000
Lifetime Max Chg Current = 2000
Lifetime Max Dsg Current = -2000
Lifetime Max Chg Power = 4966
Lifetime Max Dsg Power = -3595
Life Max AvgDsg Cur = -1000
Life Max AvgDsg Pow = -3569
Lifetime Avg Temp = 250
[Lifetime Temp Samples(System Data)]
LT Temp Samples = 5404

[Registers(Configuration)]
Operation Cfg A = 0F39
Operation Cfg B = 6540
Operation Cfg C = 0000
Permanent Fail Cfg = 5DFF
Non-Removable Cfg = 0000

[LED Cfg(LED Support)]
LED Flash Rate = 512
LED Blink Rate = 1024
LED Delay = 100
LED Hold Time = 4
CHG Flash Alarm = 10
CHG Thresh 1 = 0
CHG Thresh 2 = 20
CHG Thresh 3 = 40
CHG Thresh 4 = 60
CHG Thresh 5 = 80
DSG Flash Alarm = 10
DSG Thresh 1 = 0
DSG Thresh 2 = 20
DSG Thresh 3 = 40
DSG Thresh 4 = 60
DSG Thresh 5 = 80

[Power(Power)]
Flash Update OK Voltage = 9500
Shutdown Voltage = 9000
Shutdown Time = 10
Charger Present = 16000
Sleep Current = 10
Bus Low Time = 5
Cal Inhibit Temp Low = 50
Cal Inhibit Temp High = 450
Sleep Voltage Time = 5
Sleep Current Time = 20

[IT Cfg(Gas Gauging)]
Load Select = 3
Load Mode = 1
Term Voltage = 12000
User Rate-mA = 0
User Rate-mW = 0
Reserve Cap-mAh = 0
Reserve Cap-mWh = 0
[Current Thresholds(Gas Gauging)]
Dsg Current Threshold = 100
Chg Current Threshold = 50
Quit Current = 10
Dsg Relax Time = 1
Chg Relax Time = 60
[State(Gas Gauging)]
Qmax Cell 0 = 11450
Qmax Cell 1 = 11468
Qmax Cell 2 = 11446
Qmax Cell 3 = 11416
Qmax Pack = 11416
Update Status = 02
Avg I Last Run = -2039
Avg P Last Run = -2991
Delta Voltage = 12

[R_a0(Ra Table)]
Cell0 R_a flag = 0055
Cell0 R_a 0 = 40
Cell0 R_a 1 = 46
Cell0 R_a 2 = 55
Cell0 R_a 3 = 67
Cell0 R_a 4 = 60
Cell0 R_a 5 = 42
Cell0 R_a 6 = 51
Cell0 R_a 7 = 70
Cell0 R_a 8 = 62
Cell0 R_a 9 = 72
Cell0 R_a 10 = 91
Cell0 R_a 11 = 201
Cell0 R_a 12 = 676
Cell0 R_a 13 = 1207
Cell0 R_a 14 = 2499
[R_a1(Ra Table)]
Cell1 R_a flag = 0055
Cell1 R_a 0 = 33
Cell1 R_a 1 = 37
Cell1 R_a 2 = 46
Cell1 R_a 3 = 55
Cell1 R_a 4 = 51
Cell1 R_a 5 = 34
Cell1 R_a 6 = 42
Cell1 R_a 7 = 59
Cell1 R_a 8 = 49
Cell1 R_a 9 = 58
Cell1 R_a 10 = 76
Cell1 R_a 11 = 159
Cell1 R_a 12 = 566
Cell1 R_a 13 = 1052
Cell1 R_a 14 = 2176
[R_a2(Ra Table)]
Cell2 R_a flag = 0055
Cell2 R_a 0 = 34
Cell2 R_a 1 = 38
Cell2 R_a 2 = 46
Cell2 R_a 3 = 55
Cell2 R_a 4 = 53
Cell2 R_a 5 = 32
Cell2 R_a 6 = 40
Cell2 R_a 7 = 59
Cell2 R_a 8 = 51
Cell2 R_a 9 = 60
Cell2 R_a 10 = 76
Cell2 R_a 11 = 159
Cell2 R_a 12 = 566
Cell2 R_a 13 = 1069
Cell2 R_a 14 = 2204
[R_a3(Ra Table)]
Cell3 R_a flag = 0055
Cell3 R_a 0 = 40
Cell3 R_a 1 = 45
Cell3 R_a 2 = 53
Cell3 R_a 3 = 63
Cell3 R_a 4 = 57
Cell3 R_a 5 = 41
Cell3 R_a 6 = 49
Cell3 R_a 7 = 68
Cell3 R_a 8 = 60
Cell3 R_a 9 = 72
Cell3 R_a 10 = 88
Cell3 R_a 11 = 194
Cell3 R_a 12 = 640
Cell3 R_a 13 = 1138
Cell3 R_a 14 = 2352
[R_a0x(Ra Table)]
xCell0 R_a flag = 0000
xCell0 R_a 0 = 40
xCell0 R_a 1 = 46
xCell0 R_a 2 = 55
xCell0 R_a 3 = 67
xCell0 R_a 4 = 60
xCell0 R_a 5 = 42
xCell0 R_a 6 = 51
xCell0 R_a 7 = 70
xCell0 R_a 8 = 62
xCell0 R_a 9 = 72
xCell0 R_a 10 = 91
xCell0 R_a 11 = 201
xCell0 R_a 12 = 676
xCell0 R_a 13 = 1176
xCell0 R_a 14 = 2435
[R_a1x(Ra Table)]
xCell1 R_a flag = 0000
xCell1 R_a 0 = 33
xCell1 R_a 1 = 37
xCell1 R_a 2 = 46
xCell1 R_a 3 = 55
xCell1 R_a 4 = 51
xCell1 R_a 5 = 34
xCell1 R_a 6 = 42
xCell1 R_a 7 = 59
xCell1 R_a 8 = 49
xCell1 R_a 9 = 58
xCell1 R_a 10 = 76
xCell1 R_a 11 = 159
xCell1 R_a 12 = 566
xCell1 R_a 13 = 1040
xCell1 R_a 14 = 2151
[R_a2x(Ra Table)]
xCell2 R_a flag = 0000
xCell2 R_a 0 = 34
xCell2 R_a 1 = 38
xCell2 R_a 2 = 46
xCell2 R_a 3 = 55
xCell2 R_a 4 = 53
xCell2 R_a 5 = 32
xCell2 R_a 6 = 40
xCell2 R_a 7 = 59
xCell2 R_a 8 = 51
xCell2 R_a 9 = 60
xCell2 R_a 10 = 76
xCell2 R_a 11 = 159
xCell2 R_a 12 = 566
xCell2 R_a 13 = 989
xCell2 R_a 14 = 2039
[R_a3x(Ra Table)]
xCell3 R_a flag = 0000
xCell3 R_a 0 = 40
xCell3 R_a 1 = 45
xCell3 R_a 2 = 53
xCell3 R_a 3 = 63
xCell3 R_a 4 = 57
xCell3 R_a 5 = 41
xCell3 R_a 6 = 49
xCell3 R_a 7 = 68
xCell3 R_a 8 = 60
xCell3 R_a 9 = 72
xCell3 R_a 10 = 88
xCell3 R_a 11 = 194
xCell3 R_a 12 = 640
xCell3 R_a 13 = 1073
xCell3 R_a 14 = 2218

[Device Status Data(PF Status)]
PF Flags 1 = 0000
Fuse Flag = 0000
PF Voltage = 0
PF C4 Voltage = 0
PF C3 Voltage = 0
PF C2 Voltage = 0
PF C1 Voltage = 0
PF Current = 0
PF Temperature = 0
PF Batt Stat = 0000
PF RC-mAh = 0
PF RC-10mWh = 0
PF Chg Status = 0000
PF Safety Status = 0000
PF Flags 2 = 0000
[AFE Regs(PF Status)]
AFE Status = 00
AFE Output = 00
AFE State = 00
AFE Function = 00
AFE Cell Select = 00
AFE OLV = 00
AFE OLT = 00
AFE SCC = 00
AFE SCD = 00

[Data(Calibration)]
CC Gain = 0.9048
CC Delta = 269878.125
Ref Voltage = 2452.2
AFE Corr = 1288
AFE Pack Gain = 30625
CC Offset = -11831
Board Offset = 0
Int Temp Offset = 0
Ext1 Temp Offset = -7
Ext2 Temp Offset = -15
[Config(Calibration)]
CC Current = 3000
Voltage Signal = 16800
Temp Signal = 298.0
CC Offset Time = 250
ADC Offset Time = 32
CC Gain Time = 1000
Voltage Time = 1984
Temperature Time = 32
Cal Mode Timeout = 38400
[Temp Model(Calibration)]
Ext Coef 1 = -28285
Ext Coef 2 = 20848
Ext Coef 3 = -7537
Ext Coef 4 = 4012
Ext Min AD = 0
Ext Max Temp = 4012
Int Coef 1 = 0
Int Coef 2 = 0
Int Coef 3 = -11136
Int Coef 4 = 5754
Int Min AD = 0
Int Max Temp = 5754
[Current(Calibration)]
Filter = 239
Deadband = 3
CC Deadband = 102
CC Max Deadband = 5
CC Deadband Sample = 256
CC Max Offset Sample = 64

  • 0 in reply to Van Nguyen
    TI__Guru** 105870 points

    Hello Van,

    The gauge will take an OCV reading while in relax and cause the FCC to be recalculated. That's why a proper matched chem ID is very important, either selected through GPCCHEM or an exact match of the battery model.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 10 points

    Hi Wyatt
    The ChemID is definitely chosen correctly because it matches our cell exactly (see screenshot). This error is therefore excluded.
    Do you have any idea why these two RSOC jumps were triggered (at 75% to about 78% and at 30% to about 35%, both during relaxation)?

  • 0 in reply to Van Nguyen
    TI__Guru** 105870 points

    Hello Van,

    It can be related to calibration or Qmax as well, if the gauge is expecting less total charge the coulomb count while in active mode will be skewed in one direction. After a relaxation the voltage will correct any errors in the coulomb count itself.

    Sometimes with older cells the manufacturing process changes at some point which can also impact the OCV curve from when the cell was characterized.

    Sincerely,

    Wyatt Keller