BQ34Z100-R2: GPC CHEM ID Selection

i also want to attach the report I sent to GPCCHem tool but it doesnt let me attach it here, 

FullTest_07192023.xlsx

Hello Fahad,

Fahad Akhtar said:

Can you please make sure that I can use these results for my LFP cell (280Ah)

The obtained results can not be used. We recommend to use a chemistry cell that is match to at least 3% and below. 

Ensure that the collected IVT data looks nearly similar to this.


Note: LFP chemistries require a 24 hour relax time after fully charge. 

Fahad Akhtar said:

i also want to attach the report I sent to GPCCHem tool but it doesnt let me attach it here, 

To attach the zip, try dragging the zip folder here.

Regards,
Jose Couso

Slva725a asks for 5hours of relaxation after charge and discharge for LFP. If it needs 24hours, why has not TI fixed it's document. Where is the updated document that lists test requirements for LFP?

Needlessly to say, this is very frustrating to say the least. TI has released this product with erroneous document and firmware. And every time we run the test, TI responds with a new testing requirement. We will have to think twice in future before using TI product

FYI, I had already attached my test profile in the post above

Hello Fahad,

Fahad Akhtar said:

If it needs 24hours, why has not TI fixed it's document

Yes, we are aware that this needs to be changed. I will talk to the team about it. 

The ChemID process requires constant current and constant voltage at room temperature. The data you shared above does not follow the procedure, please see below.



1- Charge the cell to full
2- Relax for 24 hours if LFP
3- Discharge cell to terminate voltage
4- Relax for 5 hours

Regards,
Jose Couso

I discussed internally, and a 5 hour relaxation should be ok if the cell has been charged to full. If the cell is partially charged, then a 24 hour relax time is required.

Regards,
Jose Couso

What is TI definition of fully charged for an LFP cell?

We charge cell to 3.65V which is considered full in the industry. Profile I shared above is for charging up to 3.65V with constant current

Hello Fahad,

Fully charged cell is chemistry and application depended. For instance, if in your application you charge the cell up to 3.65V, then that means that is your fully charge voltage.

Regards,
Jose Couso

Sorry to say but it seems you are responding without looking at the data I am sharing. We charged cell up to 3.65V which means we just need to rest for 5hoiurs after charge. This bring us back exactly to where we started i.e. what is the problem with the testing we did and why GPChem is not identifying it as LFP and deviation is 7%?

Please talk to your experts before responding and point out exact problem in test profile so that we can fix it when we repeat it next time. Or tell us how can we send this cell to TI to generate ChemID FYI, we are based in Dallas so we can even deliver cell to desired location

Hello Fahad,

I did look at your file when you sent it. Sorry, the log file had a space in between and I missed the remaining data. I now see it completely.

Things I see in your log file:
1- Temperature is not at room -> 25ºC. It is allowed the temperature to go +- 5C. 
2- There's elapsed time jumps. This is critical and one of the requirements in the simple guide. Having elapsed time jumps is not a true five hours wait for the tool. It is recommended to have a linear increase in elapsed time




I am attaching an example zip file which shows how data should be submitted.

4885.roomtemp_rel_dis_rel.zip 

If you wish to submit your battery cell for chemistry characterization, you can contact the nearest TI sale office. I suggest you provide at least three cells.

Regards,
Jose Couso

Thanks for your reply. I didn't notice time jump, we will work on that

Regarding room temperature, it is exactly that, the temperature of the room which was around 38C when we performed the test. Are you saying that test must be performed at 25C? There is no such requirement in TI document

Hello Fahad,

Please see attached. This is from the Simple Guide to Chemical ID Selection Tool 


Standard room temperature is 25C, with +/- 5C tolerance. The temperature is critical for matching the cell. The ChemID test does a look up in the database and temperature is a factor. 

Regards,
Jose Couso