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BQ40Z60: Ra tables isn't updated

Michael Korolyov
Prodigy 180 points
Part Number: BQ40Z60
Other Parts Discussed in Thread: BQSTUDIO

Hello everyone,

My setup is bq40z60 custom board with 3s Panasonic NCR18650B cells, Charging and discharging works flawlessly.Then I process a learning cycle as described in slua777.pdf. Discharge-rest-charge stage has been completed, Qmax has been updated and Update Status has set to 0x05.

However, Ra tables never get updated while discharging, neither it does in the following rest. I've studied the Ra table update conditions, and it didn't seem they had been violated (RDIS flas was never set).

I attached the log file of my learning cycle below.

Hope for your help!BQ40Z60_learning_cycle_2nd_attempt.rar

  • 0
    TI__Guru* 76230 points

    hi Michael,

    Can you attach your gg file? In looking at your log, Resistance should have been updated. What chem id are you using and how did you identify your chem id? Did you make any changes to trace and downstream resistances? 

    I would recommend running one more cycle and try to have a constant discharge current. Your current wasn't constant although it was within the recommended c/5 to c/10 rate.

    thanks

    Onyx

  • 0 in reply to Onyx Ahiakwo
    Prodigy 180 points

    Hello Onyx,

    I've attached my gg file (exported before and after Qmax update). My chem ID is 2012 according to bqStudio "Chemistry" value for these cells. I didn't make any changes to mentioned resistances.

    I use a resistive load, but it's no problem to make a constant current one.

    Best regards,

    Michael

    BQ40Z60_learning_cycle_2nd_attempt_DF.rar

  • 0 in reply to Michael Korolyov
    TI__Guru* 76230 points
    Hi Michael,
    You have design capacity programmed to 10050mAh. I believe this is why resistance update isn't occurring. Correct the design capacity to the nominal capacity of your pack which should be closer to what your qmax value is which is 3129. For resistance tables to learn , your discharge rate has to be between c/5 and c/10. C here being the design capacity which you set to a wrong value.

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    TI__Guru* 76230 points
    Hi Michael.
    Just so you are clear,
    if you have a 2000mAh battery, if you are using a 2P config, your design capacity would be 4000mAh. If you are using 2s1P, design capacity would be 2000mAh. It is the number of parallel cells that will determine the your design capacity. For design voltage on this device, it will be the stack voltage. so for a 2P cell with each cell having a nominal of 3.6V, your design voltage would be 7200mV

    thanks
    Onyx