BQ40Z50-R2: Remaining Capacity calculation abnormal

Tin Chang

Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: GPCCHEM, GPCRB

Tool/software:

Hi,

The customer reported an issue where the battery SOC dropped to 1% too quickly. After analyzing the LOG, we confirmed that both current and temperature were stable. The issue was caused by an error in the remaining capacity calculation, which led to the sudden SOC drop. Attached is the BMS LOG from the drone operation on that day.

We received the returned battery from the customer and conducted charge and discharge tests three times, simulating the drone's conditions. However, we were unable to replicate the same phenomenon.

Therefore, we have the following questions:

Q: Given that both current and temperature are stable, what other factors could cause the RemCap calculation to deviate significantly?

Drone BMS_Log_20240709_111503.csv

RemCap calculate abnormal.gg.csv

over 1 year ago

0 Anthony over 1 year ago

TI__Mastermind 28490 points

Hello,

Can you please tell me how the chemID was acquired for this device? Was the GPCCHEM tool used?

Also, it seems like this device is consistently running at a high temperature, which could create an SOC drop. Has any temperature optimization tools been used such as the GPCRB tool on the device settings?

Regards,

Anthony Baldino

0 Tin Chang over 1 year ago in reply to Anthony

Prodigy 120 points

Hi,

Can you please tell me how the chemID was acquired for this device? Was the GPCCHEM tool used?

A: 1C charge, 0.2C discharge. Attached is use GPCCHEM tool get report.

A: The temperature at which the remaining capacity calculation anomaly starts is from 33 degrees. I think 33 degrees shouldn't be considered high temperature. I don't have used GPCRB tool to setting on the device.

Fullscreen 3513.GPC_report.txt Download

Chemistry ID selection tool, rev=2.54		
		
Configuration used in present fit:		
ProcessingType=2		
NumCellSeries=4		
ElapsedTimeColumn=0		
VoltageColumn=1		
CurrentColumn=2		
TemperatureColumn=3		
		
Best chemical ID : 3550	Best chemical ID max. deviation, % : 2.75	
		
		
		
Summary of all IDs with max. DOD deviation below 3%		
		
Chem ID	max DOD error, %	Max R deviation, ratio
3550	2.75	1.08
		
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	12.36
354	bq27411-G1C: 4.35V LiCoO2	15.25
128	bq27421-G1A: 4.2V LiCoO2	20.22
312	bq27421-G1B: 4.3V LiCoO2	28.83
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	15.03
354	bq27621:  (ALT_CHEM2) 4.35V LiCoO2	15.25
1202	bq27621: (default) 4.2V LiCoO2	18.26
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	12.36
3230	bq27426: (default) 4.35V LiCoO2	15.61
1202	bq27426: (ALT_CHEM1) 4.2V LiCoO2	18.26
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.		
		
		
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.

6237.roomtemp_rel_dis_rel.csv

+1 Anthony over 1 year ago in reply to Tin Chang

TI__Mastermind 28490 points

Hi Tin,

Tin Chang said:
A: 1C charge, 0.2C discharge. Attached is use GPCCHEM tool get report.

Thank you for sending these files, to confirm, the #3550 chemID is being used for this application? We recommend that only chemIDs below 3% error should be used, so this chemID should be fine.

Tin Chang said:
A: The temperature at which the remaining capacity calculation anomaly starts is from 33 degrees. I think 33 degrees shouldn't be considered high temperature. I don't have used GPCRB tool to setting on the device.

The instructions for the GPCRB tool can be found below. If possible, please use this tool to optimize the performance of the gauge for higher temperatures.

Fullscreen GPCRB_hi instructions.txt Download

This tool optimizes Rb_hi or Rb_low, depending on provided log file.
Learned GG file is required, and just one rel-dis-rel file at the conditions
customer likes to optimize.

Rb_hi or Rb_lo will be updated depending on the temperature in the log file.
If > 25, then Rb_hi, if <25 then Rb_lo.

Results are saved in chemdat12_IDxxx file.
Additionaly, gg file with optimized Ra and thermal parameters is saved.

How to submit the data to the server:
***************************************************

Prepare a *.zip file that contains following files:

1) config.txt (should have correct chem ID, and column assignment)
see example below:

ProcessingType=6
ChemID=3880
NumCellSeries=1
ElapsedTimeColumn=2
VoltageColumn=32
CurrentColumn=24
TemperatureColumn=22
InputChemdat12=1

Note that ProcessingType=6 shold be set so that server recognizes this new tool!

2) sysrate_rel_dis_rel.csv
(data file at discharge rate important to optimize for customer. If it is higher then 25C,
Rb_hi willbe updated in Allres_newID_xxxx, if it is lower then 25C, Rb_lo will be updated)

3) gg.csv (this should be GG file that was exported after learning, so learned Ra values are there, or file returned by rbtweak tool).

4) If from previous Rbtweak
chemdat12_IDxxx is availabe,
and gg.csv above was produced by rbtweak, rename it to chemdat12 and add it to the package, and set
InputChemdat12=1
otherwise set InputChemdat12=0

Note that input chemdat12 should be produced in Rbtweak tool with the same chem ID as specified in config.txt,
otherwise error will be reported.
All Rb_hi and Rb_low values containing in the input chemdat12 will be passed through to then new chemdat12 except the values
optimized in present run (Rb_hi or Rb_low), which will be overwritten. This way for example Rb_low values from previous
Rb tweak would be preserved, in Rb_hi is being optimized in present run.

Submit the zip file using below link:
https://www.ti.com/event/docs/accesseventaction.tsp?actionId=1503

You will receive the result by e-mail over a few minites.
It will have a zip file that contain following files:

chemdat12_IDxxx
gg_out.csv
GPC_report.txt

Use bqstudio to program original chem ID, then chemdat12_IDxxx and then the gg file to get full optimized parameters.
After that you can export golden image for production.

Regards,

Anthony Baldino

0 Tin Chang over 1 year ago in reply to Anthony

Prodigy 120 points

Hi Anthony,

the #3550 chemID is being used for this application?

A: Yes, all batteries shipped use this chemID.

Thanks, I will study how to use GPCRB tool.

Additionally, my manager asked how to prove or replicate the same situation.

0 Anthony over 1 year ago in reply to Tin Chang

TI__Mastermind 28490 points

Hi Tin,

Thank you for confirming that the correct chemID is being used.

Tin Chang said:
Additionally, my manager asked how to prove or replicate the same situation.

To prove this situation once the RB tool has been used, please run the device under the same conditions and load profile to see if this quick SOC drop occurs again.

Regards,

Anthony Baldino

Power management

Power management forum

BQ40Z50-R2: Remaining Capacity calculation abnormal