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Original question:

New CHEM_ID process and supported gauges

BQ78350-R1A: GPCCHEM Accuracy Error

Masami Akazawa
Intellectual 505 points
Part Number: BQ78350-R1A
Other Parts Discussed in Thread: GPCCHEM, BQ78350

hi, team

I will have to be excused for my poor English.


I want to know a cell chem for bq78350 OCV function at reset, so I'm using GPCCHEM, but it reported below error:

"Accuracy Error: 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"
and,
"Best chemical ID max. deviation, % : 37.36"

I checked format and units(Voltage(mV), Current(mA), Temp(deg.C)), and test schedule(charge -> relax 5 hour -> 0.1C discharge -> relax 5 hour).
And they are OK.
so I'm afraid that there isn't a match for our cell in TI chem id database.


Is there anything else I can do?
If I send you to this data file, could you please generate a new chem id for our customized cell?

Thanks.

  • 0
    TI__Guru* 77343 points

    Hi Masami,

    What type of battery chemistry are you using? Can you share your log file you loaded for the GPCCHEM tool and the output files?

    The BQ78350 is somewhat unique from some of our other battery gauges. It is a CEDV gauge, and CEDV gauges usually do not require a ChemID. However, the BQ78350 will use the ChemID to estimate the SOC after initial power-up or after a Reset. It will estimate SOC based on cell voltages only. After this point, it will track the charge in and out of the battery and estimate the SOC using the CEDV algorithm. So the CEDV parameters are much more important for this device.

    If you send your files, I can ask someone from our algorithm team to take a look to see what may be wrong.

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Intellectual 505 points

    Hi Matt,

    Thanks for your response!

    The chemistry is LFPO.

    it's difficult to share our log file in open forums, so please let me ask another question for the moment.

    I guess that there is the SOC OCV curve in DF address 0x4340-0x4391.
    If I write our cell's SOC OCV curve on the address and turn off CEDV functions, will estimating the SOC after a Reset work?
    If it will, are there other parameters I should set?
    If it won't, please let me know how to set the data of SOC after a Reset to bq78350 by myself.

    Best regards,

    Masami

  • +1 in reply to Masami Akazawa
    TI__Guru* 77343 points

    Hi Masami,

    I will send you an E2E connection request since I cannot discuss too much about the hidden ChemID settings in the public forum.

    Regards,

    Matt