BQ40Z50-R2: Reporting low Full charge capacity

Hi,

Did you calibrate the device?

Did you use the GPCCHEM tool to get a chemID match with 3% dod% error or less?

Did you complete a learning cycle and reach learned status 6?

Regards,

Evan

Hi Evan , 

Yes the Pack was calibrated 

The Cells were sent to TI for characterization , so used chem ID provided by TI

Yes Learning cycle was completed and reached status 0E

Thanks ,

AV

Hi Evan , 

We will make this change, runs tests and will Update based on the results.

Thank you,

AV

Hello,

Today's a national holiday. We will get back to you tomorrow.

Regards,

TI Apps Team

Hi Disabling the disable Relax_smooth_ok did not yield us better results .

The Variation of 2-3Ah remains , same as when the above setting was enabled .

Is there any other parameter that we can look into to avoid this jump

Thanks,

AV

Hi AV,

Can you share a .log file after disabling smoothing?

Regards,

Evan

Hi Evan , 

We had cycled it in our systems so we dont have the log file .

We will cycle it in Bqstudio and provide you with the data .

Just need to know whether you require .csv or .log file of the data ?

Thanks , 

AV

Hi Evan , 

I have attached the cycling data after disabling   Relax_smooth_ok .

Thanks ,

AV

Relax_smooth_ok-Disabled_cycles.zip

Hi AV,

The log files you sent look good, what are your concerns?

What is the expected FCC?

Regards,

Evan

Hi Evan , 

The Design capacity is 22800 mAh . And the learned Qmax values >24000 mAh .

After loading the learned GG or Srec into the battery pack ,  FCC reports >~23000mAh but during the course of battery cycling the reported FCC seems to drop and as seen in the log file around 19000mAh or 21000 or 22000 which is much lesser than the design capacity and also due to this factor it affects the SOH which is not 100% even for new battery packs .We expect the FCC to be >22800mAH also the battery is able to provide capacity >23000mAh as calculated .Is there a way to avoid these jumps in FCC and maintain stability in its value over the course of its usage.

Thanks , 

AV 

Hi AV,

Does FCC increase after every discharge cycle?

Can you log multiple discharge cycles on a single log, I would like to discuss this with my team.

Regards,

Evan

Hi Evan , 

As per your request I have uploaded a log file consisting of multiple discharge cycles in a single log .

Thanks , 

AV

cycling_log.zip

Hi Evan , 

Any findings from the data provided?

Also we have used GPCRA0 tool to produce the golden files for few of our packs , but the FCC fluctuations were seen on them as well.

We are in quite a hiccup with the FCC fluctuation issue.

Thanks , 

AV

Hi Evan , 

We are aware at the above mentioned points the FCC will update , but will the variation be around 2 to 3 Ah ?

Also another notable observation we have seen in our systems is that , when we charge with higher charging current ( around 15A) , our packs FCC jumps seems minimal , but the same pack when charged with a lower current (around 6-7 A) , the FCC jumps to a very notable difference from around 23Ah to 19Ah .Any idea as to why current level will cause such a behavior ?

Thanks , 

AV.

Pack_SREC.zip

Hi Diego , 

I have attached the .srec file. Please check and let us know your findings.

Thanks ,

AV

Hello AV,

Please allow us some time to look over the files.

Regards,

Nick 

Hi Diego , 

We agree with your point of FCC fluctuation with temperature of the pack .What is interesting in our situation is that with higher charge current (around 15A ) which results is higher temperature change, has less jump in FCC when compared to charging at lower current ( 6-7A) which results in a lower temperature change which has higher FCC jump. What could be causing this ? Are there any parameters that we could modify in the SREC that has been shared to you so as to avoid this phenomenon. 

Thanks ,

AV