BQ78PL116: Problem with Gauging Parameter Calculator

Vladimir,
The HTCF26650-3200mAh cell was characterized and released as ChemID 463. I checked for a ChemID match using the GPCCHEM tool and 463 was not in the list, but I checked it with another program and it looks like it should work. I would use that ChemID for the setup.
Tom

Hi Tom,

the actual listing in our version of bqWizard goes up to ChemID 415. I guess, that an additional file is necessary to get access to ChemID 463. Could you please tell me where to find it?

Thanks a lot,

Marcus

Here is the file for ChemID 463. There is a chemistry import feature that will allow you to import the file and then you can use it.

https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/196/0463.chem

Tom,

Thanks for posting the file, we've imported it into bqwizard and updated the bq78PL116.
Next we are running the data collection for an .aux -file to check if the selected .chem-file is improving the output of the gas gauge.

Thanks for Help!

Marcus

Hi Tom,
hi all

after selecting the suitable ChemID and generating an aux-file with our battery setup, we still have issues with the SOC readings.

When starting to discharge a fully charged battery (charge termination was controlled by "Charge Completion Pack Voltage Qualifier" and "Charge Completion Taper Current Qualifier"; minimum measured cell voltage @ EndOfCharge was 3,65Vpc ) we see a jump downwards in rel.SOC reading: SOC reads 100% during the whole rest period, but after starting discharging the SOC-value drops suddenly:

The longer the rest period since the full charge cycle, the bigger the drop of the rel.SOC. Starting discharge immediately after charge has been terminated, the deviation was almost zero. Waiting with discharge for two days, the initial SOC drop after starting discharge was -6% followed by another jump of -5% 8 minutes later. See "discharge after 2days rest.pdf"8255.discharge after 2days rest.pdf

In case the rest period is 6 full days, the initial drop was -33%(!) even the battery was still fully charged at the begin of discharging

We think, that this might come from the continousely falling OCV of the LiFePO4 battery during rest after charge was terminated. This voltage is constantly falling over a period of days. Starting at the level of fully charged (in our case 3,68Vpc) dropping to  3,349Vpc after 6 days without any kind of load connected.

Does have anyone an idea how to solve this?

Thanks,

Marcus