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BQ34Z100-R2: Learning Cycle Clarification

Rhys Phillips
Prodigy 70 points
Part Number: BQ34Z100-R2
Other Parts Discussed in Thread: BQ76942, BQ34Z100, GPCCHEM

Tool/software:

Hi, We've Just attempted our first learning cycle with our Battery Management Configuration of a BQ76942 & BQ34z100-R2, We followed the process and ended up with a failed cycle with Learned Status stuck as 0x05.

Now there are a couple of things that I've noticed are wrong that I would hopefully like some clarity on. The main thing is the voltage calibration of the Chip. There doesn't seem to be anything about this on the datasheet or technical reference manual but since we have 7 cells in series, when we go to calibrate the voltage it multiplies the calibrated voltage by 7. Should be dividing the value by 7 and then calibrating? or should be calibrate it at stack voltage and then change the Volt Scale value to be 7 to get the correct reading out?

The second big problem is that when charging and discharging after calibration the Voltage will slowly follow the Battery Voltage lagging behind by quite a bit, but after around 20-30 minutes the voltage will get 'stuck' and just not move for the rest of the charge/discharge. This is obviously going to cause an error in the Learning Cycle I would assume. If you've seen any cases similar to this you could point in our direction that would be a brilliant help.

Finally I've failed to find anywhere that specifies on what to do after a learning cycle has failed. Whats the recovery method to go back and start a new Learning Cycle?

Sorry for all the questions in the same post but appreciate all the help and support.

Kind Regards,

Rhys Philllips

  • 0
    TI__Mastermind 26545 points

    Hi Rhys Phillips,

    1) I am a little confused with your question. I recommend calibrating the gauge with a power supply, to apply a known voltage. This thread may be helpful - (+) BQ34Z100-G1: Commands for calibration procedure - Power management forum - Power management - TI E2E support forums

    2) To clarify the battery is discharging, but the gauge is reporting a voltage higher than what it should be. This could be a CC Offset error, the "stuck" part however is interesting, can you share a log file of this occurring.

    3) If your device is not properly reading voltage, current, and temperature I would fix that first. Then I am assuming you have a valid ChemID match (DOD% error 3% or less, from GPCCHEM tool or batteries characterized by us in our labs), if not it will be difficult if not impossible to complete a learning cycle. The BQ34z100 TRM has steps to complete a learning cycle and I have attached additional documentation on learning cycle. If you wish to completely reset a learning cycle you will need to upload your gauge configurations to a new (default) .srec linked below. However, once your device begins reporting the proper current, voltage, and temperature, and a learning cycle has began, even if it fails, any learned information is valid and does not have to be completely restarted with a new .srec just restart the learning cycle process.

    FW - BQ34Z100-DEVICE-FW Firmware | TI.com

    TRM - BQ34Z100-R2 Technical Reference Manual (Rev. A) (ti.com)

    Learning cycle - Achieving The Successful Learning Cycle (tij.co.jp)

    More helpful documentation - bq34z100-G1 High Cell Count and High Capacity Applications

    Regards,

    Evan

  • 0 in reply to Diego
    Prodigy 70 points

    Hi Evan,

    Thanks for your help and suggestions, I was able to solve voltage calibration issues and the voltage getting stuck was a circuit error. 

    We reset the firmware of the BQ34z100-r2 and started our learning cycle again. We followed the process and after finishing it our learned status has not changed from 05 to 06 but the information it all displays seems to be quite accurate and the Resistance tables all seem updated. I read a previous forum post saying that it can complete a successful learning cycle but not update the status, is there a way that I can know for sure its completed it successfully?

    Regards,

    Rhys

  • +1 in reply to Rhys Phillips
    TI__Mastermind 26545 points

    Hi Rhys,

    Yes, if your ra tables have updated then you have reached learned status 0x06 and have completed a successful learning cycle. Update status has been seen to get stuck sometimes but I have been unable to pinpoint why this happens yet.

    If you are unsure if the tables have updated, please send me your .srec and I can verify for you.

    Regards,

    Evan

  • 0 in reply to Diego
    Prodigy 70 points

    Hi Evan,

    Thanks for the help. We charged the battery up one more time and it ended up changing to Learned Status 0x06.

    Quick question about creating a golden image file. Can we create it whilst its in Learned status 0x06 or do we have to take it out of the learning stage to 0x02 to create one?

    Regards,

    Rhys Philips

  • +1 in reply to Rhys Phillips
    TI__Mastermind 26545 points

    Hi Rhys,

    Awesome!

    You should use the 0x06 gm.fs to create your golden image to flash other gauges with.

    Thanks,

    Evan