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BQ40Z60EVM-578: remaining capacity of battery always equals to 0

Andrei Andrei1
Prodigy 100 points
Part Number: BQ40Z60EVM-578
Other Parts Discussed in Thread: EV2400, BQSTUDIO, GPCCHEM, BQ40Z60

Hello!

i am using qb40z60, ev2400 and battery robiton lp884765 (2-series) .
When i run bqstudio, configurate necessery settings (DA settings, settings of charging, gas gauging settings), start scan and always see Relative SOC = 100%, Remaining Capacity = 0 mAh.

I tried different settings, different batteries, double-checked the switching circuit, the location of jumpers, performed charge-discharge cycles, chose different chemistry id, tried different load modes, load select, but I still do not understand why the remaining capacity is not determined. Tell me please what to look for? I would be grateful for the help!

  • 0
    TI__Guru 52115 points

    How did you choose the chemistry id?  Did you use the GPCCHEM tool to get the best matching chemistry id? 

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 100 points

    Hi Andy! Thanks for the answer!
    Before that, I took the number of the most appropriate chemistry from the table in bqStudio. After your answer, I decided to use the GPC tool. Carrying out the charge-relax-discharge-relax test, I encountered the following problem: the BQ40z60EVM board charging the battery disconnected charging at some points, pressing the reset (or unlock and restart) button in bqStudio, charging turned on and the process continued normally. Yesterday this happened when the battery was close to a full charge (constant voltage), today at the initial charging stage.
    However, I removed the log file, cut out incorrect data, received a chemistry calculation with a large error.
    I checked the settings and it is not yet clear which event stops the charge process?

    Respectfully! Andrei

  • 0 in reply to Andrei Andrei1
    Prodigy 100 points

    Andy, I saw that when the charge stopped, the XCHG bit becomes active. I will deal with the protections. On the other hand, if this is an action of the protections, then yesterday they worked under other conditions.
    Should the SOC be updated depending on the charge passed?

    Thanks!

  • 0 in reply to Andrei Andrei1
    TI__Guru 52115 points

    When you collect the data to submit to GPCCHEM, I would suggest you make sure no protections triggers. You might need to adjust some configurations.

  • 0 in reply to Andy Liu (BMS)
    Prodigy 100 points

    Thanks Andy!
    I collected data for the calculation, used  GPCCHEM tool , found the best matching chemistry id.
    But the remaining capacity is still 0 when the battery is fully charged and does not change when discharged.
    Tell me where else can I look?
    Could you show an example of bq40z60 configuration for two cells?

    2148.GPC_report.txt 
    Chemistry ID selection tool, rev=2.49		
		
Configuration used in present fit:		
ProcessingType = 2		
NumCellSeries = 2		
ElapsedTimeColumn = 0		
TemperatureColumn = 1		
VoltageColumn = 2		
CurrentColumn = 3		
		
Best chemical ID : 1576	Best chemical ID max. deviation, % : 3.98	
		
		
		
Summary of all IDs with max. DOD deviation below 3%		
		
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, %
3142	bq27421-G1D: 4.4V LiCoO2	13.76
354	bq27411-G1C: 4.35V LiCoO2	19.27
128	bq27421-G1A: 4.2V LiCoO2	33.37
312	bq27421-G1B: 4.3V LiCoO2	43.11
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	17.02
354	bq27621:  (ALT_CHEM2) 4.35V LiCoO2	19.27
1202	bq27621: (default) 4.2V LiCoO2	20.03
Best generic ID 1210		
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, %
3142	bq27426: (ALT-CHEM2) 4.4V LiCoO2	13.76
3230	bq27426: (default) 4.35V LiCoO2	19.19
1202	bq27426: (ALT_CHEM1) 4.2V LiCoO2	20.03
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.

  • 0 in reply to Andrei Andrei1
    TI__Guru 52115 points

    After you program the chemistry id, you would also need to do a learning cycle before you can get an accurate state of charge reading from the gauge device.

    See the following app note regarding how to do a leaning cycle successfully.

    https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/196/Achieving-the-Successful-Learning-Cycle.pdf

  • 0 in reply to Andy Liu (BMS)
    Prodigy 100 points

    Thanks Endy!

    Everything worked!