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Trouble getting State of charge from bq34z100-G1

Other Parts Discussed in Thread: BQ34Z100EVM, BQ34Z100-G1

Hi, 

The problem I have is that SOC is allways 0%, no matter my battery is full, relax, charging or discharging. 

I'm Working with the bq34z100EVM board attached to an EV2300 and Battery Management Studio softwarev1.3.52. My battery is Lead-Acid 12V, 6 cells and 7.0 AH. 

I have been following the step-bystep Design procedure from bq34z100-G1 datasheet. 

This are the parameters I entered to flash memory:

Design Capacity: 7000 mAh

Design Energy: 14000 mWh

Cell Charge Voltage Tx-Ty: 2087 mv (for the three of them)

Number of series cells: 6

Pack configuration: VOLSEL bit is set.

Voltage divider: 19280 mV (I can't change it soft doesn't allow me)

Flash update OK cell Volt: 2087 mV (May be this parameter wrong?)

Cell terminate voltage: 1850 mV

Load select: 0

Load Mode: 1

CHEM_ID: 0x0805

FW_VERSION: 0x0016

I'd appreciate very much your help. 

Thanks.

  • Hello Alejandro,

    Can you provide us with your gg.csv and srec files to review? I'm assuming that you're using our EVM, right?

    Design Capacity: 7000 mAh [ok]

    Design Energy: 14000 mWh [12V x 7000mAh = 84000mWh, enter 8400mWh because max value is 32767 and set Design Energy Scale = 10]

    Cell Charge Voltage Tx-Ty: 2087 mv (for the three of them) [ok typically for Lead-acid it should be ~2250 to 2300 mV/cell for standby use and 2400 to 2500 mV/cell for cycle use]

    Number of series cells: 6 [ok]

    Pack configuration: VOLSEL bit is set. [ok]

    Voltage divider: 19280 mV (I can't change it soft doesn't allow me) [ok set by calibration, that's the 16V voltage divider on EVM]

    Flash update OK cell Volt: 2087 mV (May be this parameter wrong?) [Flash Update OK Cell Volt = 2800 mV × Number Of Series Cells × 5000/Voltage Divider = 2800 mV x 6 x 5000 / 19280 mV = 4357 mV]

    Cell terminate voltage: 1850 mV [typically 10200 mV / 6 cells = 1700 mV]

     


    See pg 31 of  for other parameters that need updating when the design energy scale is changed from 1.

  • Hi Lewis, 

    Thanks for your answer.  I though I had already replied to you but I guess there was a problem with my browser.

    I have SOC working now but I still have Max error = 100% even after a cuple of charge cycles. 

    Do you know how should it go down?

    I send you the files you asked me. 

    Thanks for your support.

    Golden Image.zip

  • Hi Alejandro,

    Can you send me a log file with you charge and discharge cycles? The max error should decrease after going through successful optimization/learning cycle down to ~5% and decrease as further learning occurs. It requires discharging to empty for the lead-acid battery with rest/relaxation periods then charging to full with with rest/relaxation periods, so that OCV readings and QMax updates can occur. Please review the documents on learning cycle and send me the log file of your optimization cycles, if you're still having issues.

    2318.LearningCycleOverview.pdf

  • Hi Damian,

    I'm sorry for the delay.

    It's too bad but I haven't been loging during the charge cycle so I cant send you that file. 

    Reading the documents you recomended I realiced that in my case probably there wasn't detected the full charge condition. 

    I also notice that I can't change flash values like cell charge voltage once I have emmited IT_ENABLE comand. It returns "A read of data written failed comparison"

    There is a way to do this?

    Thank you. 

  • Hi Alejandro,

    Please check the PF status registers to ensure that there's no permanent failures (PF).  If there is, send the PF CLEAR command then the gauge will allow you to update the data flash.

  • Hi Damian, 

    I'm still working on make a learning cycle work. 

    I've done the first step, charging the battery. Anyway update_status reminds = 04. (It was like this from the beginning)

    I send you the Logs you asked. 

    At this point FC=1, VOK=0, QFN=1, RUP_DIS=0

    Max Error= 100%

    Now I plan to go to the next step but I'm not sure if at this point it's all ok because update_status should be =1. 

    Once again, thanks for your help.

    Charging.rar

  • Hi again, 

    Now I did the discharging process. 

    I send log files.

    Max error is still 100% 

    Regards6232.Logs.rar

  • Hello Alejandro,

    You need to do two full discharge cycles with sufficient relaxation to get Ra and Qmax updates for the Max error update to occur.

    • Turn on logging
    • Full discharge to ~10.2V or cell/pack termination voltage at C/5 to C/10
    • Relax for 5hrs
    • Full charge to ~14.4V or cell/pack max charge voltage
    • Relax for 2hrs
    • Full discharge to ~10.2V or cell/pack termination voltage
    • Relax for 5hrs
    • Turn off logging

    You can check the Alert register for OCVTAKEN bit to see if it gets cleared on entering relax mode and set before exiting relax mode as well as VOK.