BQ20Z45 Learning failed, VOK never set

Hi,
How did you determine that chem id 297 is your correct id? The first step to have learning cycle complete successfully is to carry out chemid identifcation. Link on how to do that below:
www.ti.com/.../GPCCHEM

then for your discharge, i would recommend using c/7... C/5 seems is on the border and I have seen that cause learning to fail.
thanks
Onyx

Hi Onyx,

I find the VOK issue is caused by the bq Evaluation Software, when I update bq Evaluation Software version from 00.09.59 to 00.09.64, VOK can set correctly. I confirmed the chem id with local FAE, chem id 0297 is correct for LG INR18650 B4 2600mAh.

We use C/5 to discharge for learning in many products, I don't think this is the root reason. I redo two learning cycle, but still get a learning failed result after charging and discharging, Update Status is strange. Please see below Step7 and Step9.

Step1: Program .senc file with correct chemical ID, correct data flash, cycle count and update status are 0, max error is100%.

Step2: Calibrate the battery pack.

Step3: Discharge the battery pack to empty with C/5 (voltage down to term).

Step4: Wait 5 hours.

Step5: Send IT enable command (0021) , Bits QEN is set and VOK is set.

Step6: Charge pack to full with C/2 until the taper current is reached and the FC bit is set.

Step7: Let it relax for 2 hours.(Qmax is updated, Update status is 0D, Max Error keeps 3%)

Step8: Discharge the pack down to term voltage with C/5.

Step9: Let it relax for 10 hours.(Qmax is not updated, Update status keeps 0D, Max Error keeps 3%, Ra table is updated but R_a flag = 0555)

GG File Export.zip

2402.Learning-Log-Data.xlsx

resistance flag of 0555 means you had resistance update occur before qmax update. Qmax update has to occur first. It seems you may have enabled IT at some point before starting the test. redo your test, but use a c/7 constant current discharge. Also, program the default senc file, then program the chem id, configure data flash before starting the test.

thanks
Onyx

There is three chem id for LG INR18650 B4, can you explain what's the difference?

Hi,

I would recommend you use our tool gpc chem to determine which of the three is a better fit, but going off the nomenclature, i think the second one is the correct one.

www.ti.com/.../GPCCHEM


thanks
Onyx

Hi Onyx,

See from the INR18650 B4 cell spec, the max charge voltage is 4.2V, but chem id 0260 is 4.3V charge voltage. Can you explain why do you think 0260 is the correct chem id? I will try to use gpc.

i was going off the nomenclature. To be absolutely certain use the gpcchem tool. Also, make sure to charge to the max voltage stated in the batteries data sheet.
thanks
Onyx

Hi Onyx,

I tried to use chem id 0230 and 0260 to do learning cycle, but when finished first cycle charging and relaxing for more than 7 hours, Qmax was not updated, Update Status was 04, Max Error was 100%.

Also, I used C/7 to discharge, the chem id was 0297 at this time. After first cycle charging and relaxing, Qmax was updated, Update Status was 0D, Max Error was 3%. However, when finished first cycle discharging and relaxing for more than 10 hours,  Qmax was not updated, Update Status was 0D, Max Error was 3%.

It's possible that chem id is none of 0230, 0260, 0297?

i had recommended using the gpc chem tool to determine which is the best match. You should be able to use your log files from your learning cycle.

www.ti.com/.../gpcchem

thanks
Onyx

Hi Onyx,

Thanks for your help. I submit my learning log data to gpc chem tool, Best chemical ID is 230. Should I use chem ID 230 to do learning cycle?

Chemistry ID selection tool, rev=2.24  
  
Configuration used in present fit:  
ProcessingType=2  
NumCellSeries=3  
ElapsedTimeColumn=0  
VoltageColumn=1  
CurrentColumn=2  
TemperatureColumn=3  
  
Best chemical ID : 230 Best chemical ID max. deviation, % : 1.23 
  
  
  
Summary of all IDs with max. DOD deviation below 3%  
  
Chem ID max DOD error, % Max R deviation, ratio
230 1.23 0.52
1352 1.74 0.15
2079 1.9 0.27
295 1.92 0.57
231 1.95 0.39
253 2.04 0.22
1647 2.09 0.38
1340 2.12 0.26
297 2.19 0.17
2053 2.22 0.14
2089 2.25 0.21
275 2.27 1.52
221 2.29 0.21
1323 2.34 0.22
1653 2.37 0.53
239 2.41 0.25
2078 2.45 1.92
2077 2.46 0.49
252 2.47 0.33
1331 2.54 0.22
245 2.55 0.16
2051 2.56 0.92
1300 2.57 0.16
1253 2.59 0.22
1280 2.59 0.9
218 2.6 0.47
2007 2.65 0.33
1301 2.65 0.17
2025 2.69 0.26
260 2.7 0.15
286 2.71 0.32
2091 2.72 0.21
3385 2.72 0.9
206 2.73 0.27
2102 2.75 0.7
2148 2.81 0.31
257 2.86 0.3
269 2.86 0.2
2084 2.9 0.24
1325 2.91 0.25
1351 2.92 0.35
1594 2.92 0.92
  
Max. deviations for best ID is within recommended range. Chosen best chemical ID is suitable for programming the gauge.  
  
  
Selection of best generic ID for ROM based devices like bq274xx  
  
  
Device / Family #1  
Generic Chem ID Device/ Voltage/ Chemistry max DOD error, %
354 bq27411-G1C: 4.35V LiCoO2 13.78
3142 bq27421-G1D: 4.4V LiCoO2 16.16
128 bq27421-G1A: 4.2V LiCoO2 34.77
312 bq27421-G1B: 4.3V LiCoO2 43.68
Best generic ID 354  
Warning: Deviation for best generic ID is above recommended level for this device / family. Consider using another device, flash based gauge or RAM programming of custom ID.  
  
  
Device / Family #2  
Generic Chem ID Device/ Voltage/ Chemistry max DOD error, %
1210 bq27621:  (ALT_CHEM1) 4.3V LiCoO2 12.83
354 bq27621:  (ALT_CHEM2) 4.35V LiCoO2 13.78
1202 bq27621: (default) 4.2V LiCoO2 18.69
Best generic ID 1210  
Warning: Deviation for best generic ID is above recommended level for this device / family. Consider using another device, flash based gauge or RAM programming of custom ID.  
  
  
Device / Family #3  
Generic Chem ID Device/ Voltage/ Chemistry max DOD error, %
3142 bq27426: (ALT-CHEM2) 4.4V LiCoO2 16.16
3230 bq27426: (default) 4.35V LiCoO2 17.12
1202 bq27426: (ALT_CHEM1) 4.2V LiCoO2 18.69
Best generic ID 3142  
Warning: Generic ID Deviation is so high that it is most likely due to anomaly in the data. Please check that data files have recomended format, units and test schedule  
  
  
Warning: First OCVpoint has non-zero current I=  -0.003 Please make sure you have a 2 hr relaxation period before the beginning of discharge.  
Warning: Last OCVpoint has non-zero current I=  -0.003 Please make sure you have a 5 hr relaxation period after the end of discharge.  

yes, pls use chem id 230 for your learning cycle.
thanks
Onyx

Hi Onyx,

 Actually, I have done the learning with chemical id 230 one week ago, learning result is failed, may be it's not the ID issue. Do you have any other suggest except the ID and C/7 discharg current?

I follow the Simple Guide to Chemical ID Selection Tool (GPC) to charge and discharge, the result shows that "Best chemical ID : 1352 Best chemical ID max. deviation, % : 1.11 ". The chemical ID is confusing.

Chemistry ID selection tool, rev=2.25

Configuration used in present fit:
ProcessingType=2
NumCellSeries=3
ElapsedTimeColumn=0
VoltageColumn=1
CurrentColumn=2
TemperatureColumn=3

Best chemical ID : 1352 Best chemical ID max. deviation, % : 1.11



Summary of all IDs with max. DOD deviation below 3%

Chem ID max DOD error, % Max R deviation, ratio
1352 1.11 0.49
2053 1.19 0.42
1340 1.4 0.93
206 1.41 0.85
297 1.45 0.27
1351 1.46 0.75
221 1.47 0.39
1653 1.51 0.26
1647 1.51 0.51
1331 1.52 0.42
2025 1.52 1.37
230 1.56 0.81
2089 1.58 0.75
295 1.59 0.59
260 1.61 0.21
2078 1.61 1.09
2051 1.61 0.8
2102 1.64 0.22
2079 1.72 0.16
253 1.74 0.29
2084 1.76 1.33
1323 1.77 0.34
2041 1.78 2.54
218 1.8 0.63
239 1.89 0.42
3385 1.9 0.95
2007 1.92 1.11
1267 1.93 0.6
252 1.94 0.39
1301 1.95 0.97
1325 1.95 0.44
275 1.96 1.39
231 1.98 0.4
1253 2 0.26
245 2.02 0.34
1300 2.03 0.26
2077 2.05 0.62
2091 2.16 0.28
261 2.19 0.57
234 2.19 0.48
2148 2.25 0.35
2094 2.27 1.32
208 2.3 0.31
200 2.3 0.31
203 2.3 0.31
1332 2.37 0.5
2106 2.38 0.87
2082 2.39 0.3
264 2.42 0.45
286 2.45 0.32
1268 2.46 2.32
257 2.46 0.46
1280 2.51 0.96
2023 2.59 0.78
1282 2.62 0.55
1594 2.63 0.42
2048 2.78 0.33
247 2.82 0.6
2066 2.89 0.36
2047 2.99 0.45

Max. deviations for best ID is within recommended range. Chosen best chemical ID is suitable for programming the gauge.


Selection of best generic ID for ROM based devices like bq274xx


Device / Family #1
Generic Chem ID Device/ Voltage/ Chemistry max DOD error, %
354 bq27411-G1C: 4.35V LiCoO2 12.81
3142 bq27421-G1D: 4.4V LiCoO2 14.51
128 bq27421-G1A: 4.2V LiCoO2 30.93
312 bq27421-G1B: 4.3V LiCoO2 39.83
Best generic ID 354
Warning: Deviation for best generic ID is above recommended level for this device / family. Consider using another device, flash based gauge or RAM programming of custom ID.


Device / Family #2
Generic Chem ID Device/ Voltage/ Chemistry max DOD error, %
354 bq27621: (ALT_CHEM2) 4.35V LiCoO2 12.81
1210 bq27621: (ALT_CHEM1) 4.3V LiCoO2 14.51
1202 bq27621: (default) 4.2V LiCoO2 18.53
Best generic ID 354
Warning: Deviation for best generic ID is above recommended level for this device / family. Consider using another device, flash based gauge or RAM programming of custom ID.


Device / Family #3
Generic Chem ID Device/ Voltage/ Chemistry max DOD error, %
3230 bq27426: (default) 4.35V LiCoO2 13
3142 bq27426: (ALT-CHEM2) 4.4V LiCoO2 14.51
1202 bq27426: (ALT_CHEM1) 4.2V LiCoO2 18.53
Best generic ID 3230
Warning: Deviation for best generic ID is above recommended level for this device / family. Consider using another device, flash based gauge or RAM programming of custom ID.

 

The GPCCHEM tool shows that ChemID 230 should be a good match to your cell and you mentioned that you tried running an optimization cycle using this ChemID. Could you send the log file for this run?

I tried to do learning cycle with Chemical ID 230 twice, but all failed, I did not log data. The GPC tool shows 1352 and 230 two different ID for the cell, it's confusing. I still consider the ID is 297 for INR18650 B4 2600mAh.

I did two learning cycle successfully with Chem ID 297 by changing CC Deadband to a smaller value as 3.5uV. Is that say CC Deadband must be set to a very small value for Qmax update? For example, my design capacity 2600mA, sense resistor 2mΩ, C/5 discharge, discharge time+relax time=10h, CC deband must<5.2uV( 2600mAh*1%/10h*2mΩ), it's that correct?

Good afternoon !
Faced the problem of updating Qmax. Controller BQ20z45. He conducted on the description of more than 20 discharge-charge cycles. But the status of more than 04 does not change. Tried different files of chemistry. I suspect the problem with a maximum capacity error and a DOD capacity error. Could you put the file bq20z45_r1_0105_bld_0005 with these 2 parameters open.