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BQ34Z100-G1: BQ34Z100-G1 Remaining Capacity of the batteries could slowly decline during storing

Star Xu
Genius 9645 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQ34Z100

Hi

My customer produce 200pcs 12series cells. After all batteries are assembled, calibrate and turn on IT_Enable, the battery power is basically around 72%.The battery was left in the warehouse for 4 days to check the power, and it was found that the SOC of almost all the batteries was reduced by at least 10%, and quite a few  reduced more than 20%.

To troubleshoot problems, they took one piece of batteries do test,  send x0041, SOC will return to 72%, and then  use BQstdio continuously log the battery data, found that RemainingCapacity fell by a numerical, about 50 minutes in this way, the rate of SOC must be at least a 2% drop in one day. And the rate of decline is not the same, some fast, some slow.The battery he tested was slow.

The problem is that, except for the remains of voltage and temperature and the zero current, if the SOC is reduced by Remaining Capacity, I do not know what caused the slow decline of RemainingCapacity.

The batteries have been storing there for 12 days now, and some have dropped to 10 percent with the same voltage. And some batteries have Cycle count become 1.

There's a small number of batteries SOC goes down for a while, and all of a sudden it goes back up to about 72%, and then it goes down again, and Cyclecount has become 1.

https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/196/2311.0117_5F00_2.7z

Attached log file and RA-table

The battery ChemID is: 203

 before the trial production, the customer assembled several batteries by themselves, and now these batteries have been used for dozens of cycles, without this phenomenon.As these batteries did not stand at the beginning, I do not know whether there will be this phenomenon at the beginning.

Please give some suggestion.

Thanks

Star

  • 0
    TI__Mastermind 42535 points

    Hi Star,

    Looking at the Ra table, the cell resistances have been very unusual. While the Ra drop to Ra 4 is expected, the values are expected to increase after that. How did they find out their cell chem ID? The default Ra table for ID 203 looks like this,

    Cell0 R_a 0 = 74
    Cell0 R_a 1 = 80
    Cell0 R_a 2 = 90
    Cell0 R_a 3 = 96
    Cell0 R_a 4 = 78
    Cell0 R_a 5 = 80
    Cell0 R_a 6 = 82
    Cell0 R_a 7 = 85
    Cell0 R_a 8 = 87
    Cell0 R_a 9 = 89
    Cell0 R_a 10 = 96
    Cell0 R_a 11 = 114
    Cell0 R_a 12 = 135
    Cell0 R_a 13 = 187
    Cell0 R_a 14 = 643

    You should expect something similar to that. I also see that their voltage is fluctuating between 53340 and 53326 and goes back to 53340. In one day you can get remcap simulations in rest which also depend on OCV. So, this may along with their ID, and learning data affect the gauge.

  • 0 in reply to Batt
    Prodigy 100 points

    Hi Batt,

    First,Thank you for your help. Do you mean my ChemID is not correct? Battery manufacturers do not know their battery's ChemID.So I got the ChemID through the GPC tool.Now,I upload my ChenID report file.

    Fullscreen 4186.GPC_report.txt Download 
    Chemistry ID selection tool, rev=2.47		
		
Configuration used in present fit:		
ProcessingType=2		
NumCellSeries=14		
ElapsedTimeColumn=0			
VoltageColumn=1			
CurrentColumn=2			
TemperatureColumn=3		
		
Best chemical ID : 203	Best chemical ID max. deviation, % : 1.14	
		
		
		
Summary of all IDs with max. DOD deviation below 3%		
		
Chem ID	max DOD error, %	Max R deviation, ratio
203	1.14	1.78
200	1.14	1.78
208	1.14	1.78
2131	1.18	0.5
257	1.28	0.36
2094	1.35	1.24
245	1.38	1.38
2106	1.4	1.31
1741	1.41	1.16
1982	1.49	-12.96
2407	1.55	1.53
1253	1.58	0.29
2102	1.63	0.77
2047	1.64	0.81
1976	1.64	1.3
1323	1.7	0.5
1954	1.71	1.13
234	1.75	0.98
261	1.82	1.59
1325	1.89	0.69
269	1.89	1.15
2135	1.92	1.24
239	1.93	0.79
1991	1.95	0.8
217	1.98	1.35
2127	1.99	0.76
2286	2.03	0.89
253	2.03	0.91
2302	2.05	0.93
2188	2.08	1.21
2394	2.08	1.81
2151	2.09	0.56
225	2.12	0.57
265	2.18	1.88
227	2.23	1.86
242	2.33	0.59
1331	2.36	1.75
231	2.46	1.05
1301	2.47	1.63
2079	2.47	1.08
1340	2.5	1.58
2082	2.6	0.93
286	2.62	-9.49
1975	2.7	0.88
252	2.71	1.51
201	2.72	0.44
2066	2.84	1.22
1314	2.86	0.97
3596	2.9	1.08
263	2.92	0.89
		
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, %
3142	bq27421-G1D: 4.4V LiCoO2	8.77
354	bq27411-G1C: 4.35V LiCoO2	10.74
128	bq27421-G1A: 4.2V LiCoO2	26.49
312	bq27421-G1B: 4.3V LiCoO2	35.99
Best generic ID 3142		
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	10.74
1202	bq27621: (default) 4.2V LiCoO2	14.27
1210	bq27621:  (ALT_CHEM1) 4.3V LiCoO2	14.85
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, %
3142	bq27426: (ALT-CHEM2) 4.4V LiCoO2	8.77
3230	bq27426: (default) 4.35V LiCoO2	11.61
1202	bq27426: (ALT_CHEM1) 4.2V LiCoO2	14.27
Best generic ID 3142		
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.

    roomtemp_rel_dis_rel.csv

    By using chemical ID 203, my Learning Cycle was successful.Moreover,The batteries we used are power batteries with high discharge rates.The actual application current is about 100A.So  we scaled the current 10 times.As you see in the file named "roomtemp_rel_dis_rel.csv",The discharge current is 175 mA.Actually,the discharge current is 1750mA.In the case of high rate discharge, the RAtable will be updated very small like the picture I uploaded before.

    In addition, I do not know why voltage is fluctuating between 53340 and 53326.Maybe it's because the voltage is not being detected correctly by BQ34Z100-G1.

    The problem of a slowly drop in Remaining Capacity only occurs in the new batteries with no used.However,the old batteries with several times cycle do not have this phenomenon.

    I have one more question.Can IT_Enable commomd send immediately after the current calibration is completed? or we must wait for OCV.

    Thanks,

    Xie

  • 0 in reply to XIE XiChun
    TI__Mastermind 42535 points

    Hi Xie,

    With scaling you are actually losing resolution and accuracy. It is possible that if the batteries have fluctuating voltages, this can contribute to the error. Please make sure that your connections are good and there are no solder blobs etc that can influence the measured input values.

    Your chem ID is good. The ID 203 is the best ID for your cell. You can send IT enable immediately after the calibration is completed. Then you can wait for OCV so that a DOD point will be set for gauging when you start your learning cycle to update the battery parameters.

  • 0 in reply to Batt
    Prodigy 100 points

    Hi Batt,

    Thanks for your anwser.

    But,Even if there are problems with poor connectivity or solder blobs etc .But it's impossible that every battery has the same problem.

    Through careful logdata analysis, I found that the decrease or increase  of Qmax Passed Q and DOD0 Passed Q resulted in the decrease or increase of RemainingCapacity. But I do not know why Qmax Passed Q and DOD0 Passed Q changed.

    Now, I do a new learningCycle and make a new GoldenFile.This problem remains.I attached the Memory_Data of new  GoldenFile with no cycles.It  contains RA Table and configuration information.Could you please help me to  find the reason of this problem?

    I have some other questions.How is SOH calculated? And How configuration the parameter "SOH Load I"?

    Thanks!

    Regards,

    Xie.

    0044.1123.gg.csv

  • 0 in reply to XIE XiChun
    TI__Mastermind 42535 points

    Hi Xie,

    Please confirm that you ran the chem ID match on the new cells. Qmax Passed Q and DOD Passed Q will change when the gauge detects passed chg or dsg. They are reset to 0 on a Qmax or DOD update.

    SOH is calculated as the ratio of FCC/Design capacity. SOH Load I is the load current that is used for SOH calculations.

  • 0 in reply to Batt
    Prodigy 100 points

    Hi Batt,

    Back to my first problem.The change in SOC is caused by RemainingCapacity's change.The change in RemainingCapacity is caused by Qmax Passed Q and DOD Passed Q .You sead  that Qmax Passed Q and DOD Passed Q will change when the gauge detects passed chg or dsg.But the log data show that there are no current during batteries's standing.Is there something wrong with my hardware circuit design?This problem has been bothering me for a long time.The product is about to go into mass production.So,I wish you can help me solve this problem.

    Attached hardware circuit and PCBLayout.

    Today,I make once ChemID learningCycle.The best ChemID become 2106.

    Fullscreen 0636.GPC_report.txt Download 
    Chemistry ID selection tool, rev=2.48		
		
Configuration used in present fit:		
ProcessingType=2		
NumCellSeries=14		
ElapsedTimeColumn=0			
VoltageColumn=1			
CurrentColumn=2			
TemperatureColumn=3		
		
Best chemical ID : 2106	Best chemical ID max. deviation, % : 0.77	
		
		
		
Summary of all IDs with max. DOD deviation below 3%		
		
Chem ID	max DOD error, %	Max R deviation, ratio
2106	0.77	2.47
2094	0.83	2.13
1253	0.93	0.79
2568	1.08	2.46
1325	1.12	1.42
1323	1.15	0.92
200	1.17	4.11
208	1.17	4.11
203	1.17	4.11
245	1.26	2.11
2442	1.27	1.37
1976	1.36	1.18
257	1.37	0.66
1741	1.46	3.04
2084	1.46	6.66
234	1.49	1.99
217	1.5	1.05
2552	1.56	1.42
1954	1.58	1.2
2407	1.59	4.61
2405	1.6	4.62
2131	1.61	0.7
239	1.61	0.93
253	1.61	1.33
1982	1.64	-7.11
2579	1.68	1.39
2286	1.7	1.42
2102	1.7	0.6
2135	1.72	1.27
2302	1.74	0.87
2520	1.75	0.72
2487	1.8	2.26
2078	1.8	3.88
1267	1.82	2.68
2309	1.83	4.66
212	1.84	6.07
2047	1.89	4.29
1991	1.92	1.67
2082	1.95	1.74
227	1.96	1.83
225	1.96	0.47
2188	1.98	1.82
295	1.98	2.32
1996	2	5.62
275	2.01	5.61
1351	2.01	4.11
1594	2.01	4.31
2151	2.01	0.49
218	2.04	2.69
1647	2.06	3.91
1331	2.07	3.23
269	2.07	2
1653	2.08	3.07
2394	2.08	0.93
2127	2.1	0.63
261	2.11	1.4
1280	2.12	4.11
2066	2.12	2.11
260	2.14	7.06
1340	2.17	2.66
2051	2.17	3.5
2023	2.18	3.27
2025	2.19	7.58
264	2.27	4.58
2079	2.29	1.06
242	2.34	0.56
297	2.35	2.9
265	2.38	3.33
1268	2.4	9.91
1282	2.41	2.56
286	2.42	-2.94
252	2.5	1.88
2077	2.51	5.13
231	2.55	1.48
230	2.56	4.52
1352	2.61	3.14
1321	2.72	2.19
1300	2.77	5.3
1301	2.78	2.47
201	2.96	3.69
		
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, %
3142	bq27421-G1D: 4.4V LiCoO2	9.05
354	bq27411-G1C: 4.35V LiCoO2	11.42
128	bq27421-G1A: 4.2V LiCoO2	26.42
312	bq27421-G1B: 4.3V LiCoO2	33.57
Best generic ID 3142		
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	10.22
354	bq27621:  (ALT_CHEM2) 4.35V LiCoO2	11.42
1202	bq27621: (default) 4.2V LiCoO2	11.93
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	9.05
3230	bq27426: (default) 4.35V LiCoO2	11.77
1202	bq27426: (ALT_CHEM1) 4.2V LiCoO2	11.93
Best generic ID 3142		
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.

    8078.roomtemp_rel_dis_rel.csvThis confused me.

    Thanks!

    Regards,

    Xie.

  • 0 in reply to XIE XiChun
    TI__Mastermind 42535 points

    Hi Xie,

    You have used many sense resistors in parallel. This configuration is not supported and will lead to error. The bq34z100 supports a 10mOhm sense resistor. Please use that in your design. The chem ID 2106 is the best ID for your battery.