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Original question:

BQ40Z50-R1: OC Flag & Internal Charge Counter

BQ40Z50-R1: Cycle count not increasing - BQ40z50-R1

Nitin Ghige
Prodigy 170 points
Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: BQSTUDIO

I have below questions on internal discharge counter in BQ40z50-R1.

Can we access discharge counter in BQ40z50-R1?

I am trying to understand how Cycle count increment works.

Is the discharge counter reset if CUV flag raised?

I am depleting the battery till the CUV raised and charging the battery to 100%. I did this multiple time but cant see cycle count increments (it is 0 always).

I have verified my settings like

GAUGE_EN = 1

Update status = 0x0E

Cycle count percetage = 90%

Please let me know if any other settings to be checked.

  • 0
    TI__Guru* 77283 points

    Hi Nitin,

    The cycle count percentage is the percentage of FullChargeCapacity or DesignCapacity depending on the setting of the CCT bit in the IT Gauging Configuration. At 90%, that means that the amount of charge counted by the coulomb counter must be 90%, so this is not based on a voltage threshold like CUV.

    I recommend logging the discharge from full charge to monitor the registers to see if Remaining Capacity changes by 90% of the Design Capacity. In bqStudio, you can log the registers and you can also export a .gg.csv (Data Memory) file periodically during the discharge to see how the flash parameters are updating. The frequency for the logging and the data memory exports can be set in the Window->Preferences menu.

    Best regards,
    Matt

  • 0 in reply to Matt Sunna
    Prodigy 170 points
    Thank you Matt resolving my queries,
    I am logging discharge and charge cycles to see Remaining Capacity and all other parameters.

    Few more details:
    CCT bit configured to use Design capacity. So the charge counted by the coloumb counter must be 90% of design capacity to increment the CycleCount.

    My design capacity is 15120mWh
    Full charge capacity is 12670 mWh.
    So may be the coloumb counter not reaching to 13608mWh (90% of design capacity) in one discharge cycle. So more cumulative discharge in 2nd dischage cycle should increment my CycleCount.
    The Cyclecount increment is working perfect in my batteries.

    I have few batteries where Cycle count is not increasing from 0.

    I had depleted those batteres till the CUV raised and charged them to 100%. I did this multiple time but cant see cycle count increments (it is 0 always).
    I wanted to know that the completed discharge till the battery fully depleted and CUV raised can cause coloumb counter to reset.

    Is any way to access coloumb counter using TI tool?
  • 0 in reply to Matt Sunna
    Prodigy 170 points
    Thank you Matt resolving my queries,
    I am logging discharge and charge cycles to see Remaining Capacity and all other parameters.

    Few more details:
    CCT bit configured to use Design capacity. So the charge counted by the coloumb counter must be 90% of design capacity to increment the CycleCount.

    My design capacity is 15120mWh
    Full charge capacity is 12670 mWh.
    So may be the coloumb counter not reaching to 13608mWh (90% of design capacity) in one discharge cycle. So more cumulative discharge in 2nd dischage cycle should increment my CycleCount.
    The Cyclecount increment is working perfect in my batteries.

    I have few batteries where Cycle count is not increasing from 0.

    I had depleted those batteres till the CUV raised and charged them to 100%. I did this multiple time but cant see cycle count increments (it is 0 always).
    I wanted to know that the completed discharge till the battery fully depleted and CUV raised can cause coloumb counter to reset.

    Is any way to access coloumb counter using TI tool?
  • 0 in reply to Nitin Ghige
    TI__Guru* 77283 points
    Hi Nitin,

    The "Gauge Status 2" command 0x0074 returns a parameter "DOD0 Passed Q". This parameter will give the accumulated charge since the last DOD reading. This will give you a good idea where to set the cycle count %.

    This command is a block read and returns a large amount of information. I think this parameter might be present in the bqStudio log file, so it might be easiest to monitor it from there.

    Best regards,
    Matt
  • 0 in reply to Matt Sunna
    Prodigy 170 points
    Good information!.
    I followed "DOD0 Passed Q" parameter and found consistent. Cyclecount incremented when "DOD0 Passed Q" showed change of 90% of Design capacity (it takes one complete discharge and second half discharge)
    But out of my 10 batteries, 2 batteries always showing Cyclecount 0, even after number of charge and discharge cycles.

    I believe we do not have access to specific CHARGE COUNTER based on which CycleCount increments.

    I am not sure what is wrong with my few batteries. May be some GG settings or May be something else? Can you please list out all GG settings and any flag need to be checked for CycleCount working?
  • 0 in reply to Nitin Ghige
    TI__Guru* 77283 points
    Hi Nitin,

    Can you send the logs for the 2 batteries where the cycle count is not incrementing? The DOD0 Passed Q is the correct parameter to monitor.
    The settings that you may want to adjust are the Cycle Count % (you can lower this value to see if the issue is resolved on the 2 batteries) and setting the CCT bit in 'IT Gauging Configuration' to 1 (this sets whether 90% of Design Capacity or 90% of FCC is used).

    How close was the DOD0 Passed Q to 90%?

    Thanks,
    Matt
  • 0 in reply to Matt Sunna
    Prodigy 170 points

    Hi Matt,

    I will be sharing log files soon.

    While doing charge and discharge cycles on battery, the cyclecount increased to 1 from 0. I am still executing more charge/discharge to observe next increment of Cyclecount.

    I think everything is working good but trying to understand why it took so long to increase CycleCount from 0 to 1.

    Are there any conditions due to which the Discharge Counter can reset (Counter on which Cyclecount is implemented)?

    shutdown command? Reset command? Battery depleted below Term Voltage? CUV set?

    1. Suppose I discharged the battery 50% and sent to shutdown. later day I woke up the battery and discharged another 50%. Will it increase the cycle count?

    2. Suppose I discharged the battery 50% and applied reset. later day I discharged another 50%. Will it increase the cycle count?

    3. Suppose I discharged the battery fully till the term voltage reached, CUV set and battery output cutoff. "DOD0 passed Q" reached to 80% of design capacity (CycleCountPercentage is 90%). Later I charged the battery. I was expecting 10% more discharge should increment Cyclecount. Is this correct?

    Regards,

    Nitin

  • 0 in reply to Nitin Ghige
    TI__Guru* 77283 points
    Hi Nitin,

    Internally, the gauge tracks and accumulates the amount of passed current during discharge. Unfortunately, you cannot read this value directly, so DOD0 Passed Q is a way to estimate this during a constant discharge. So even if you charge/discharge by smaller amounts, the cycle count will increase once this reaches the value defined by the cycle count %. So for your first example, the cycle count should increment.

    Shutdown and reset commands might clear this passed charge counter (I'm not 100% sure, but it would take me some time to verify). Are you issuing shutdown or reset commands during your experiment? Also, why is the battery hitting CUV (the default is 2.5V)?

    Regards,
    Matt
  • 0 in reply to Matt Sunna
    Prodigy 170 points

    The batteries were used in a device which can send the battery to shutdown. After ~4 charge & discharge cycles executed on the battery, the Cyclecount observed 0 an did not see increment. During these discharge cycles, the device might have sent batteries to shutdown (possible, battery takes long time to charge and discharge which cannot take place within same day, so operator may have put the device into shutdown which in results the battery sent to shutdown).

    We beleive, sending battery to shutdown should not reset the discharge counter.

    I have tested this scenario,  I applied shutdown command within discharge run and found "DOD0 passed Q" reset to 0. But not sure about internal Discharge counter. (Hope you will confirm it). I am also verifying that by executing below experiment.

    Discharge battery to 80%. Send battery to shutdown. Wake up battery charge for some time and discharge another 20-30%. This should increase the Cycle count if internal Discharge counter do not reset on shutdown command.

    About CUV question:

    Below are settings for our Two cells battery.

    CUV = 2900mV

    Term Voltage = 6000 mV

    So while discharging, we deplet the battery fully, where CUV set and then battery output do cutoff.

    Actually we are charging the battery to 100% then discharging the battery fully, till the battery output cutoff and expecting to increase the CycleCount.

    Again, as our CC percentage is 90% of design capacity (see note below), the Discharge_Counter will not reach to its threshold in one discharge run. Hence we are executing second dischrage run and expecting to increase the CycleCount in 2nd discharge run. Its working and verified but somehow did not work on 2 battries (May be something wrong with those 2 batteries or Test sequence, not sure at this point).

    Note : We are charging the battery with 8V instead 8.2V therefore our FCC is 85% of Design capacity and hence the one complete discharge run the Discharge Counter reaches to only 85% of Design capacity. The remaining 5% counted in 2nd discharge run.

     

    Below are few questions for you:

    What are internal Discharge counter reset conditions? sutdown command, Reset command, Term voltage reached, any other flags set etc.

    Do you see anything wrong with the implementation?

    Regards,

    Nitin

  • 0 in reply to Nitin Ghige
    TI__Guru* 77283 points
    Hi Nitin,

    Shutdown or Reset will reset this counter since it is not a data flash value. Since you are only charging the battery to 85%, it would probably make more sense to set the Cycle Count percentage to a lower value like 75% since you will never cover the full range with one discharge.

    Regards,
    Matt
  • 0 in reply to Matt Sunna
    Prodigy 170 points
    Hi Matt,
    From my experiment results, it seems Shutdown command reset the discharge counter. Thank you for confirming at your side.

    I also want to find out if any other conditions can reset the discharge counter. Specially if any protection flags raise condition?


    Thank you again for your suggestion. I will rethink to define our Cycle Count percentage.
  • 0 in reply to Nitin Ghige
    TI__Guru* 77283 points
    Hi Nitin,

    I just confirmed with the firmware engineer for this device. The discharge counter will not reset outside of shutdown.

    The accumulated discharge value cannot be read externally, but it increases at the same rate at which Remaining Capacity decreases (during discharge).

    Regards,
    Matt
  • 0 in reply to Matt Sunna
    Prodigy 170 points

    Thank you for your timely support.

    My issue is resolved.  Cycle count was not increasing because operator might have sent battery into shutdown during discharge cycles.

    We dint know that sending to shutdown can reset the Discharge counter.

    Regards,

    Nitin