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BQ40Z80: Problem with calibration process

Mateusz Kujawinski
Prodigy 20 points
Part Number: BQ40Z80
Other Parts Discussed in Thread: GPCRA0

Hi,

During the execution of the learning cycle according to the instructions for the LI-NMC battery (Kokam), the Istatus register stops at the value of 5 or 6. Despite several attempts, the lstatus value of 14 cannot be achieved. Checked for different values of charging and discharging currents from the allowed ranges and also for a different entered capacity (as according to the load the battery has a bit more than the declared 53Ah the value of 60 was also entered for testing). Despite repeating the learning process ( fully clearing the Flash memory by uploading the factory firmware and setting the desired register values from the beginning) and/or continuing the charge/discharge cycle the lstatus register stops at the previously mentioned values.

I attach the collected logs for calibration processes with different conditions.

logi.zip

Best regards,
Mateusz Kujawiński

  • 0
    TI__Guru** 105590 points

    Hello Mateusz,

    This gauge only supports up to 32000mAh without doing a scale factor on the current, can you clarify all the steps you took for doing the actual current calibration and share your .gg file?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    Hello Wyatt,

    Thank you for fast reply.

    Scale factor for current was set to 2. The learning cycle was carried out in accordance with the instructions in:  SLUA848–June 2018 "How to Complete a Successful Learning Cycle for the bq40z80". In addition, the effects for lower charging currents and for other discharge current values (from the range of C/5 - C/10) were also checked. I attach the gg file with the currently set parameters. As I wrote in the previous message, the nominal capacity and manufacturing status have been changed. Previously, many attempts were made for different current values from the allowed ranges for the set nominal value of the capacitance. Each attempt ended in failure.
    5618.data_memory.gg.csv
    Best regards,
    Mateusz Kujawiński
  • 0 in reply to Mateusz Kujawinski
    TI__Guru** 105590 points

    Hello Mateusz,

    The scale factor set in the gauge data flash? Please try using without this scale factor and manually inducing the factor by calibrating the current artificially (apply 4A, tell the gauge it's 2A for example) Sometimes the scale factor in the gauge may impact the accuracy.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    Hi Wayatt,

    Unfortunately, despite the fact of setting the scale factor to 0 and scaling the current manually the lstatus bit stuck on 5. We tried to redo the chg->dsg again and the value is still 5. CHG current was 20A and 26.5 A, DSG current was 8 A. Logs from the failed learning process and data memory before and after that process are attached. 
    noscalefactor_learning.zip

    Best regards,

    Mateusz Kujawiński

  • 0 in reply to Mateusz Kujawinski
    TI__Guru** 105590 points

    Hello Mateusz,

    I don't see any specific conditions that would disqualify this cycle from learning the Ra table. What you can do instead of trying to get update status to 0x06 with the gauge is to take these logs and submit them to the GPCRA0 tool which will give you the Ra table. Just make sure you submit the initial .gg file from before learning. The output from GPCRA0 will provide the learned Ra table.

    Sincerely,

    Wyatt Keller