BQ40Z50: BQ40Z50 Error: negative low temperature resistance observed, R=-0.204374298831174 usually caused by wrong chem ID selection 0 0

Hello,

I am not able to access the files through those links. If possible, please attached the compressed folders to the next message. They can be drag and dropped in.

Regards,

Anthony Baldino 

Send to TI (GPCRB)seal-18650-3s2p-3000-2024-3-12-5h.zip   seal-18650-3s2p-3000-2024-3-10-2 -5h-report(1).zip

HI TI team.

       I reuploaded the attachment ，  Please  help me check what the problem is? Is it related to the rest time after full charge?or do I need to change the way I test the low temperature？

Send to TI (GPCRB)seal-18650-3s2p-3000-2024-3-12 -24h-0℃.zipSend to TI (GPCRB)seal-18650-3s2p-3000-2024-3-12 -24h-0℃-report.zip ，

This is the latest data sent to TI. Since the lithium iron battery is used, in order to obtain stable OCV, after full charge, we let the battery rest for 24h before discharging. Will this have any impact?

Hello,

Thank you for sending that data.

Can you please confirm that the data is not being manipulated before being entered into the GPCRB tool? Changing the data before entering it into the tool can occasionally cause the negative resistance issue.

Regards,

Anthony Baldino

Hello,

     5810.Send to TI (GPCRB)seal-18650-3s2p-3000-2024-3-12 -24h-0℃.zipSend to TI (GPCRB)seal-18650-3s2p-3000-2024-3-12 -24h-0℃-report(1).zip

  1、  I didn't change the data,the test is a lithium iron battery(3S2P), the voltage difference before low temperature discharge and after discharge rest is very small, whether this will affect the calculation of GPCRB,I have never encountered such errors in SOC low temperature optimization before.Can you help me to confirm which of my data will cause GPCRB calculation anomalies?

  2、The actual capacity of the battery is about 3200mAh, and the QMAX 4692mAh suggested in TI's reply report. Could you please help confirm that the gg file in TI's reply report can be used?

Hello,

I do not believe that .gg should be used. A difference in the Qmax and Design Capacity is acceptable but a difference that large should not occur. Looking through all the low temp test, there is this large dip in temperature in multiple tests during the relax period that looks out of the ordinary. Can you please go into depth about this occurrence?

Also, looking into the .gg file, I see that Quit Current is set to 0mA. This will make entering relax very difficult for the gauge. Can you please go into more detail of why this is set to that value?

Regards,

Anthony Baldino

Hello

     1、  3 hours before discharge, during the relax, the temperature of the incubator was lowered, but since we wanted the battery to have a longer relax period, we returned to normal temperature. But during the discharge the temperature is 0℃. Does this affect the results of the low temperature optimization calculation?  

     2、This gg.file  is also made with the help of TI. It is difficult for guage to enter the relax mode, will it affect the result of low temperature optimization? Is it because greater power consumption under relax will affect test results

Hello,

When the low temp test is being completed, the gauge should predominantly be at the lowered operating temperature for the entirety of the test. There will be times during charge and discharge where the temperature measurements will spike due to the cell itself, however outside of that it should be at the lowered temperature.

Regarding the quit current, it seems like the gauge is able to enter relax with no error based on the data above, so I do not think this is the root cause of the current issue.

Regards,

Anthony Baldino