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optimization cycle in BQ34z110

P niranjan
Intellectual 360 points

I am trying to do a optimiszation cycle for a 12V 4500AH battery.  Even though I have run 3 cycles there is no change in the update status. I am checking the control status and flags register, VOK, QEN and OCVTAKEN flags are working properly, as given on the datasheet. But the update status is not getting updated.

1. My discharging rate is a little a lower then c/10, its around c/12. Is that a problem?

2. Is there any particular charge rate?

3. My SOH is stuck with 98%, what might be the problem?

The follwoing is my learning process:

1. Charge the battery for full. 2 hours relaxation

2. reset and set IT enable.

3. Discharge the battery till the cell voltage reached 1600mV. 5 hours relaxation

4. Enable IT.(in one the post it was mentioned to enable IT, at this point of time to)

5. Charging to full. 2 hours relaxation.

6. Discharge the battery to zero.

What might be the problem?

  • 0
    TI__Guru 73830 points

    1. The discharge rate must be greater than C/10. We have been recommending C/8.

    2. The charge rate is not as important. Make sure that you let it taper to to C/100.

    3. Not at this point.

    1. You need to let the pack relax until the OCVTAKEN flag gets set.

    2. You should not have to reset and send IT ENABLE, if QEN and VOK are set.

    3. We recommend discharging to about 500mV below the Cell Term Voltage * # of cells.

    4. You should not do this during the cycle.

    5. Relax until OCVTAKEN flag is set.

    6. Never discharge to zero. Discharge to 500mV below the Cell Term Voltage * # of cells.

    Can you send me the log data and gg file and I will check it for other issues?

  • 0 in reply to ThomasCosby
    Intellectual 360 points

    Thanks Tom.

    I will upload the gg file and the log file. 

    Meanwhile, just a little confirmation. OCV flag should be taken during both Charging and also Discharging cycle is it? 

  • 0 in reply to ThomasCosby
    Intellectual 360 points

    The following is my learning cycle.

    1. Charge the battery and relax till OCVTAKEN.

    2. IT enable.

    3. Discharge the battery. 500mV below cell terminate voltage at the rate of c/8.

    4. relaxation time 5 hours or till VOK flag is cleared and OCV flag is set.

    5. Charge the battery and relax till OCVTAKEN.

    6. Discharge the battery. 500mV below cell terminate voltage at the rate of c/8.

    Please let me know, the above steps are okay.

  • 0 in reply to P niranjan
    TI__Guru 73830 points

    2. You should not have to send the IT Enable, if you sent it previously and waited until the OCVTAKEN flag is set. It should hurt to send it this time though.

    3. The term voltage is cell based, so discharge to 500mV below to stack term voltage. I.e. If the cell TRM voltage is 2000mV and you have a 6S configuration, then you will discharge to 11500mV.

    4. Wait until the OCVTAKEN flag is set, even if it is linger than 5 hours.

    6. Same comment as 3.

    You should also disable the FConvEn bit in the Operation Cfg B register during the Optimization cycle.

    Make sure that the Flash Update OK voltage is set to 1000mV.

  • 0 in reply to ThomasCosby
    Intellectual 360 points

    2. This is where I am actually enabling IT. In the datasheet, I have noted that, we were supposed to start the optimization cycle with a fully charged battery. 

    will that be okay?

  • 0 in reply to ThomasCosby
    Intellectual 700 points

    Tom,

    1. Can we do optimization cycle with varable load?

    2. Our application of usage is variable load( Peak Current 14A,  5AH battery), so optimization cycle need to be run on variable load ?

  • 0 in reply to ARUN DEV Neelakantan potty
    TI__Guru 73830 points

    Arun

    You will need to run the optimization cycle with a constant current load that is between C/10 and C/5.

    Tom

  • 0 in reply to ThomasCosby
    Intellectual 700 points

    Tom,

    1) We have generated a .ROM file after doing the optimization cycle.

    2) During optimization cycle we stopped the discharge load at 10.2V ( Current = 600mA)

    3) Voltage Recovered back to 11.3V.

    4) In the actual system load, the lower cut in voltage is 11.3V.

    5) Our low battery indication is at 30%.

    6) We have loaded the new golden data to 7 samples.

    7) We have kept 7 samples with same load( 600mA), 2 samples showed 30% indication near to 11.4V and 5 samples showed 30% indication at 11.8V.

    8) The Low Battery Indication time was very less in two units.

    9) Kindly help us to rectify the above problem.

    Regards,

    Arun Dev

  • 0 in reply to ARUN DEV Neelakantan potty
    TI__Guru 73830 points
    Arun,
    What problem are you trying to correct? The SOC showing 30% for 11.3V and 11.8V or the Low Battery indication or something else? I think taht you are using ChemID 800 and the SOC should be in the 30% range for pack voltages around 11.8V.

    Tom
  • 0 in reply to ThomasCosby
    Intellectual 700 points
    TOM,
    Yes, SOC showing 30% at 11.4V and at 11.8V. Out of 7 5 showed at 11.8V and 2 showed at 11.4V.
    Why it showed at 11.4V only?

    Arun Dev
  • 0 in reply to ARUN DEV Neelakantan potty
    TI__Guru 73830 points
    If you can send a senc file from each of these two packs, then I will try to find out what is different.