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BQ34Z100-G1 Learning Cycle - Learned Status won't update to 0x05

Juan Pablo DT
Prodigy 130 points
Part Number: BQ34Z100-G1

We have been following the learning cycle as described in a previous post. We are able to fully charge our pack and the OCVTAKEN flag is set at which point we start the discharge cycle. This is where we have tried a couple of different things without success:

We fully discharged the batteries ~600 mV below the 'Cell Terminate Voltage'

- at a rate of C/20 (as suggested by this post) AND

- at a C/8 rate as suggested by the initial post

We waited until the OCVTAKEN updated but neither QMax updates nor Learned Status changes to 0x05.

Is there something we may have set incorrectly that could prevent this update? We do have a leakage current that we can't control as it is an always ON device (battery is the backup source), could this be the issue?

I've gone through a few of the posts and tried a few other things without success. Any advice would be appreciated, logs for the latest discharge, charge, discharge cycles are attached.

BatteryCycleLogs.zip

  • 0
    TI__Mastermind 34775 points

    Hi Juan,

    Can you provide your gg.csv and srec for us to review your settings? Did you reach charge termination and FC flag was set?

    see 7.3.11 Charging and Charge Termination Indication on page 37 of the datasheet.

  • 0 in reply to Damian Lewis
    Prodigy 130 points

    Hello Damian,

    I do believe I reached charge termination, the FC bit was set but I will double check everything from what you pointed me too in the datasheet.

    I've just completed another discharge cycle at C/20 without success so it must be something we're missing.

    I have attached the gg.csv and .srec files as requested.

    Thanks and best regards,

    Juan Pablo

    GaugeSettings.zip

  • 0 in reply to Juan Pablo DT
    TI__Mastermind 34775 points

    Hi Juan,

    Thanks for the files. Also pay attention to VOK and QEN flags to ensure they are set to 1. Qmax is updated after the charging portion of the learning cycle when the is cell relax.

    I will review the files and get back to you on Monday.

  • 0 in reply to Damian Lewis
    Prodigy 130 points

    Hello Damian,


    Thanks for the reply, I did double check that we reached charge termination and indeed we do. The FC flag is set and CHG becomes 0; one thing I noted is that once the OCVTAKEN flag is set the VOK flag goes low (after it was set for the whole charge cycle), is this expected behaviour?

    I charged the battery pack over the weekend to make sure charge termination was reached and will attempt a discharge cycle at C/8 tomorrow first thing. Please let me know if you have any further insight.
    Just to clarify from response, the Learned Status will not update after the discharge cycle but only after charging following the initial discharge cycle, correct?

    Thanks!
    Juan Pablo

  • 0 in reply to Damian Lewis
    Prodigy 130 points

    Hello,

    I would really appreciate an update on this one.

    Thanks,


    Juan Pablo

  • 0 in reply to Damian Lewis
    Prodigy 130 points

    Hello,

    We've tweaked the parameters in an attempt to get this issue resolved with no luck so far. I've found a couple of other threads that mention that when OCVTAKEN is set, VOK must update to zero? This is what happens in our case, yet 'Learned Status' remains zero.
    For the Min Cell Voltage, after calculations we obtain a voltage larger than 2800 mV which is suggested in previous threads, is this the cell voltage or Pack voltage  (not entirely clear in the Datasheet).

    I attach our latest srec.

    Thanks,

    Juan Pablo bq34z100-G1_VT.zip

  • 0 in reply to Juan Pablo DT
    TI__Guru 73830 points
    Juan Pablo,
    Please send the log file, if you have it, but the problem is probably the Flash Update OK Voltage. It should be set to about 100mV, since you are using PbA cells.
    Tom
  • 0 in reply to ThomasCosby
    Prodigy 130 points
    Hello Tom,

    I just went through the latest log files and it looks like they did not save properly (some issue with the USB driver). However, the update settings remain as with my initial post.
    I will re-start the cycle with 100 mV and post the logs when I get them (probably tomorrow).
    Thanks,
    Juan Pablo