• State Resolved
  • Locked Locked
  • Replies 14 replies
  • Answers 1 answer
  • Subscribers 65 subscribers
  • Views 551 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ34Z100-G1: Failing to estimate SoC with precision

Andres Suarez
Prodigy 150 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQSTUDIO

Hello,

I'm trying to use the BQ34Z100-G1 to supervise a battery of LiFEPo4 -12.8V and 9AH. The load that has to manage this battery is dynamic, for example, a current pulse of 3A, then 0.6A for five minutes and finally 1A for 2 hours. I did the test to identify the chemistry of the battery and then the learning 

I followed the recommendations mentioned here http://www.ti.com/lit/an/slua948/slua948.pdf for dynamic loads. Selecting the Load mode = 0 (Constant current) and Load Select = 3 (Low pass filtered average load). In resume, this is the configuration that I'm using:

registers_values_Rev.2.gg.csv

To test the behavior of the gauge I carried out two tests, the first one with constant load and the second one emulating the load of my final product. Getting the following results:

(Ignore the spikes in the charts, That's a measurement problem)

The jumps up in the estimation of the SoC shouldn't happen if I active the SMOOTH mode in the gauge. Here's my problem, why does the SoC deviate so much? The error of this device is supposed to be small. Exist another configuration that I have to do to improve the prediction of the gauge when I'm using dynamic load?

I would very much appreciate help in optimizing the operation of this device for dynamic load.

Thanks a lot,

Andres Suarez

  • 0
    TI__Guru 52115 points

    Hi Andres,

    Could you provide bqStudio logs files for your two tests?  I would like to check the SOC accuracy. 

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 150 points

    Hi Andy,

    Do you check the log file that I upload? Please let me know to see if I need to open another forum to ask again.

  • 0 in reply to Andres Suarez
    TI__Mastermind 24870 points

    Let me follow up with Andy.

  • 0 in reply to Andres Suarez
    TI__Guru 52115 points

    Hi Andres,

    Sorry, I have been occupied by a few urgent issues recently. I will try to take a look at your files today and provide some feedback.

    Andy

  • 0 in reply to Andy Liu (BMS)
    TI__Guru 52115 points

    Hi Andres,

    I just took a look at this file "ConstantLoad.csv". I the SoC begins with 63%.

    Do you have the entire log file in which discharge starts after the battery is fully charged and rests for over 2 hours?

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 150 points

    Here is another test with those conditions DCH_BAT4_1.txt

  • 0 in reply to Andres Suarez
    TI__Mastermind 24870 points

    Hello Andres,

    How did you find the chemistry ID for the device? Do you have a gg file or srec file you can attach?

  • 0 in reply to Kang Kang
    Prodigy 150 points

    Hello Kang,

    The chemical ID was made by a college last year. He used this log file: 3603.roomtemp_rel_dis_rel_1.csv

    How ever, I tried to repeat the chemical ID with the values specified in this guide of texas instruments http://www.tij.co.jp/jp/lit/an/slva725a/slva725a.pdf and I am not able to obtain a good chemical ID. The only differences between the two tests are the Stop voltage and the Discharge Current.

    Item Chemical ID Old Chemical ID New
    Charge Voltage (V) 14.6

    14.6
    Nominal Capacity (mAh) 9000 9000
    Discharge Stop Voltage (V) 10.5 10
    Discharge Current (A) 1.5 0.9

    The reports obtained with the Texas Instrument tool are the follows: 

    Chemical ID - September 2019:  

    Fullscreen GPC_report_Old.txt Download 
    Chemistry ID selection tool, rev=2.49		
		
Configuration used in present fit:		
ProcessingType = 2		
NumCellSeries = 4		
ElapsedTimeColumn= 0		
VoltageColumn = 1		
CurrentColumn = 2		
TemperatureColumn = 3		
		
Best chemical ID : 457	Best chemical ID max. deviation, % : 7.71	
		
		
		
Summary of all IDs with max. DOD deviation below 15%		
		
Chem ID	max DOD error, %	Max R deviation, ratio
457	7.71	0.19
400	11.62	0.6
435	12.63	0.48
6106	12.66	0.34
478	13.53	0.03
414	13.9	0.76
462	14.1	0.46
464	14.35	0.42
		
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	35.26
3142	bq27421-G1D: 4.4V LiCoO2	35.77
128	bq27421-G1A: 4.2V LiCoO2	3238.2
312	bq27421-G1B: 4.3V LiCoO2	4942.99
Best generic ID 354		
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		
		
		
Device / Family #2		
Generic Chem ID	Device/ Voltage/ Chemistry	max DOD error, %
354	bq27621:  (ALT_CHEM2) 4.35V LiCoO2	35.26
1210	bq27621:  (ALT_CHEM1) 4.3V LiCoO2	42.94
1202	bq27621: (default) 4.2V LiCoO2	2864.32
Best generic ID 354		
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		
		
		
Device / Family #3		
Generic Chem ID	Device/ Voltage/ Chemistry	max DOD error, %
3230	bq27426: (default) 4.35V LiCoO2	29.38
3142	bq27426: (ALT-CHEM2) 4.4V LiCoO2	35.77
1202	bq27426: (ALT_CHEM1) 4.2V LiCoO2	2864.32
Best generic ID 3230		
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		
		
       0	0		
Warning: voltage in V detected	 divider changed to 1		
Warning: current in A detected	 divider changed to 1	0

    Chemical ID - February 2020: 

    Fullscreen GPC_report_New.txt Download 
    Chemistry ID selection tool, rev=2.49		
		
Configuration used in present fit:		
ProcessingType = 2		
NumCellSeries = 4		
ElapsedTimeColumn= 0		
VoltageColumn = 1		
CurrentColumn = 2		
TemperatureColumn = 3		
		
Best chemical ID : 435	Best chemical ID max. deviation, % : 15.57	
		
		
		
Summary of all IDs with max. DOD deviation below 15%		
		
Chem ID	max DOD error, %	Max R deviation, ratio
0	0	0
		
Warning: Deviation is above recommended level. New chem ID needs to be released for this cell. Please contact your TI representative to send the cell to Dallas for characterization		
		
		
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	29.94
3142	bq27421-G1D: 4.4V LiCoO2	32.38
128	bq27421-G1A: 4.2V LiCoO2	4048.96
312	bq27421-G1B: 4.3V LiCoO2	6562.15
Best generic ID 354		
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		
		
		
Device / Family #2		
Generic Chem ID	Device/ Voltage/ Chemistry	max DOD error, %
354	bq27621:  (ALT_CHEM2) 4.35V LiCoO2	29.94
1202	bq27621: (default) 4.2V LiCoO2	30.18
1210	bq27621:  (ALT_CHEM1) 4.3V LiCoO2	31.13
Best generic ID 354		
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		
		
		
Device / Family #3		
Generic Chem ID	Device/ Voltage/ Chemistry	max DOD error, %
3230	bq27426: (default) 4.35V LiCoO2	28.98
1202	bq27426: (ALT_CHEM1) 4.2V LiCoO2	30.18
3142	bq27426: (ALT-CHEM2) 4.4V LiCoO2	32.38
Best generic ID 3230		
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

    This is the gg file used to run the tests mentioned before: registers_values_Ext_Rev.1.gg.csv

  • 0 in reply to Andres Suarez
    TI__Genius 12215 points

    Hi, Andres

        According to your previous post, you have enabled smoothing function, right?

        Have checked the reset counter before and after these SOC jumps, as I also see communication error occurred around these SOC jumping points, could this caused by reset?

        If you have not enabled smoothing function, please try enable it

  • 0 in reply to Steven Yao
    Prodigy 150 points

    Hi,

    Yes, I enabled the smoothing function. This SOC behavior it shouldn't be like this if the smoothing function is activated.

    Regarding the reset counter, can you explain with more detail how to get the value of that counter? Because I can not find anything like a reset counter in the BQ34Z100-G1 datasheet.

    Thanks for the help,

    AS

  • 0 in reply to Andres Suarez
    TI__Genius 12215 points

    Andres

        The reset counter is private, need to check srec file to find this value before and after SOC jump.

        You can also monitor the voltage at VREGIN pin see if the voltage sudden drop when dynamic load is applied. 

  • 0 in reply to Steven Yao
    Prodigy 150 points

    Steven,

    How I can check the srec file? uploading the firmware into the Gauge again? there is no way to check the reset counter with a command?

  • 0 in reply to Andres Suarez
    TI__Genius 12215 points

    Andres

        The reset counter is contained somewhere in the srec file, you can find its location by doing this:

        1: Export the srec file first, and save it

        2: Then restore the device to normal mode and export the srec file again.

        These srec files are basically text file, you can compare these 2 files with some comparing tools like beyond compare, if you find one byte incremented by 1, then that should be the location of reset counter.