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BQ40Z80: How to complete a successful learning cycle on bq40z80

Simone Nodari
Prodigy 30 points
Part Number: BQ40Z80
Other Parts Discussed in Thread: BQSTUDIO, GPCCHEM

I'm attempting to complete a learning cycle on a BQ40z80 battery gauge as detailed on SLUA848 application report.

No problems completing successfully the sequences detailed in par. 4.2.1 (discharge to empty), 4.2.2 (Relax for at  least 5h),

4.2.3 (Charge battery to full).

But when doing what is detailed on 4.2.4 paragraph (Relax for at least 2h) what I'm observing is that the BQ40z80

sets correctly the REST flag indicator, but it doesn't advance its LStatus() from 0x4 to 0x5 as pointed out in the application report.

What to do now?

I've to restart the whole procedure one more time? And why, i.e. which is the missing step that doesn't permit the LStatus() increment to 0x5 value?

Thanks in advance to all,

Simone.

  • 0
    TI__Guru** 102415 points

    Hello Simone,

    Can you share a bqStudio log of your learning cycle attempt with your .gg file from before and after the cycle? This is the fastest way for us to debug learning cycle questions.

    Most commonly the issue is one of a few things:

    1. Wrong chem ID programmed (GPCCHEM tool wasn't used)
    2. Didn't cycle the battery by 90% DOD for a Qmax update
    3. The data flash parameters were not updated according to the battery
    4. Discharge current was too high or too low for Ra update (second part of learning cycle)

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 30 points

    Hello Wyatt,

    I have a zip file that contains all the relevant logs and a gg file of our gauge. 

    I hope it is useful to detect my faults!

    Thanks a lot!!!!

    Simone.

    bq40z80_logs.zip

  • 0 in reply to Simone Nodari
    TI__Guru** 102415 points

    Hello Simone,

    From the logs I cannot tell if you got a good OCV reading after the discharge, it can take up to 5 hours for the voltage to stabilize and take a valid OCV reading.

    You should see a change of DOD0 of at least 90% (of 2^14 range) otherwise it will not be successful. Can you also share your GPCCHEM report and data?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 30 points

    Hello Wyatt,

    regarding the chemistry of the used battery cells the attached image shows that is programmed as Samsung INR18650-30Q.

    You think that I've to redo the full discharge phase of the learning cycle?

    I'm pretty sure that at the end of the discharge phase the REST signal was asserted!

    Thanks in advance,

    Simone

  • 0 in reply to Simone Nodari
    TI__Guru** 102415 points

    Hello Simone,

    Is this the exact same battery you have in your system? If not, you should use the GPCCHEM tool to find the best match. Just matching the capacity and chemistry will lead to errors.

    The gauge may have become rested during the learning cycle, but that does not mean it has gotten a 90% change in DOD between the two rest periods. This is in the "Delta Capacity" description in the document you are using (SLUA848) 4.1 Initial Qmax Update Criteria.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 30 points

    Hello Wyatt,

    the battery is exactly the same!

    Here it is....

  • 0 in reply to Simone Nodari
    TI__Guru** 102415 points

    Hello Simone,

    If the battery is exactly the same manufacturer number, then chances are it is a close match.

    Are you able to see a 90% change in DOD0 for the cells between rest periods? The range is 0 to 2^14. usually a successful range is DOD0 ~ 0-500 (full charge) and DOD0 ~ 16000 (full discharge).

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 30 points

    Hello Wyatt,

    today I restarted a learning cycle. The full discharge cycle is expected to end in few hours (it discharges the battery at C/5 rate..) and the DOD0 counter

    is actually measuring the battery discharge capacity....i.e. it started with 0 and now is counting up to the full discharge capacity of the battery pack.

    I'm logging all data and I hope to complete correctly this learning cycle (LStatus 4...5...6....to 14 value!).

    Thanks,

    Simone

  • 0 in reply to Simone Nodari
    TI__Guru** 102415 points

    Hello Simone,

    Share the log and .gg data if you run into any other issues.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Intellectual 360 points

    Hi Wyatt,

    I'm working with Simone on the battery. Now the LTstatus is 5. We will upload the logs in the next days.