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BQ34Z100-G1: power-on reset after charging

Van_Ng
Prodigy 120 points
Part Number: BQ34Z100-G1

Hi 

We are using the BQ34z100-G1 (with a golden flash image) for the power management of our PbA battery pac (22Ah)

I have a question regarding a hardware power cycle of the device.

What happens with the device if  a power cycle (CE and REGIN pin) is applied after 1 year of regular usage with charging and discharging sequence?

- Does this trigger a full reset? 

- Does this have an adverse effect on the accuracy of SOC?

- Which setting parameters are applied after this kind of reset? from the uploaded golden image?

Thanks in advance

Van

 

  • 0
    TI__Guru** 105600 points

    Hello Van,

    In the power cycle you're disconnecting the gauge from power? After a disconnection of power and re-connection the gauge will POR and will re-initialize to the settings you have in the Golden Image.

    The bq34z100-g1 is an impedance track gauge so it should still track your SOC accurately.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 120 points

    Hello Wyatt,

    That's correct the gauge will be shortly disconnected and reconnected.

    If I understand you correctly, the Qmax and Ra table will set back to the initial values (from the golden flash image). 

    In this case, the SOC won't be accurate because the initial Qmax and Ra table does not reflect the correct state of the battery (1year in use, Qmax is lower than at the beginning). Is this correct?

    Additional question, if I run another optimization cycle , will this overwrite my current golden flash image on my battery? or will it just update the Qmax and Ra table?

    thanks, 

    Van

  • 0 in reply to Van_Ng
    TI__Guru** 105600 points

    Hello Van,

    The Qmax updated periodically is actually saved in Dataflash so you will not need to update it or run another cycle, if this was a ROM based gauge the value would be reset.

    You shouldn't need to do another cycle, the gauge should continue to update Qmax normally after the reset.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 120 points

    Hello Wyatt

    For example, my Qmax is set to 10000mAh on the golden flash image. After one year of usage the Qmax is reduced to 8000mAh. So, which Qmax value will be taken by the gauge after a power reset?

    We had an issue with a device. The battery was fully charged but the SOC was showing 0%.  After the power reset, the SOC was changed to 50%.

    I would like to understand why this could happen.

    Thanks 

  • 0 in reply to Van_Ng
    TI__Guru** 105600 points

    Hello Van,

    The Design capacity should be set in your golden image, the Qmax is a separate value. It will use the Qmax your battery had before the POR.

    Do you have any data logs of this? Before the reset the gauge was reading 0%? Could you also provide the .gg file.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 120 points

    Hello Wyatt

    Unfortunately, I don't have any data logs. (Btw, do you know how long it can be logged?)

    That's correct. Before the reset the gauge was reading 0% and after the reset it was reading 50%.

    Do you have any idea what could have happen?

    Sincerely,

    Van

  • 0 in reply to Van_Ng
    TI__Guru** 105600 points

    Hello Van,

    It should be able to log for a few days with the default settings, you can increase the sampling interval for longer periods.

    If the battery was fully charged before the POR and it was reading 0% SOC, there was a problem before the POR.

    If you are able to, I would try cycling the system to see if SOC updates correctly after an in field Qmax update and log the process. You can perform another learning cycle, that will be a sure way to get the system back working, but I'm not sure why it was reading 0% SOC when fully charged before the POR.

    Are you able to extract the .gg file?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 120 points

    Hi Wyatt,

    I don't have access to the device. So, I'm not able to extract the .gg file. 

    However, I will provide you my original gg file and my charger setting? maybe you can recognize bad design.

    Please note, that gauge does not communicate with charger device during charging.gg_file_and_charger_settings.zip

  • 0 in reply to Van_Ng
    TI__Guru** 105600 points

    Hello Van,

    What is the design capacity of your system? What are the specifications of the battery? Did you do the POR because the SOC was 0% when the battery was charged?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 120 points

    Hi Wyatt

    The capacity is 22000mAh (lead crystal battery, type 6-CNFJ-22, 2 in series, 24V).

    The POR was executed because the SOC was 0% after a "successful" charging indicated by the charger. 

    The battery is charged by an independent charger with it own parameter settings and control of the charge cycle.

    Charger and fuel gauge do not communicate with each other during charging. I assume that this circumstance may have adverse effect.

    Additionally, the affected fuel gauge was not sealed and its current measurement was not calibrated (voltage measurement was calibrated).

    Sincerely,

    Van

  • 0 in reply to Van_Ng
    TI__Guru 52115 points
    I see the following settings in your gg file.
    "Configuration","Charge Termination","Taper Current","100","mAmp"
    "Gas Gauging","Current Thresholds","Dsg Current Threshold","60","mAmp"
    "Gas Gauging","Current Thresholds","Chg Current Threshold","75","mAmp"
    "Gas Gauging","Current Thresholds","Quit Current","400","mAmp"
    According to our app note below.
    the following conditions must be met
    Charge Term Taper Current > Chg Current Threshold > Quit Current.
    I would suggest you change the Quit Current to a value below Chg Current Threshold.
  • 0 in reply to Andy Liu (BMS)
    Prodigy 120 points

    Hi Andy,

    which threshold levels in terms of tapper, Dsg, Chg and Quit current would you recommend for my application? 

    Thanks

    Van

  • 0 in reply to Van_Ng
    TI__Guru** 105600 points

    Hello Van,

    The app note outlines what your values should be according to your battery capacity (C) your capacity is 22Ah so a value of C/10 is 2.2A. By reading through section 2 of the app note Andy linked you should be able to setup the gauge correctly for your application.

    I don't know your charger's taper current but one option would be the following setup:

    Charge Term Taper Current (C/10-C/100) = C/40 = 550mA

    Charge Current Threshold (Chg Curr Thrsh < Chrg Term Taper Curr) = C/50 = 440mA

    Quit Current ( < C/20) = C/60 = 360mA

    It depends on what your charger has set for it's taper current because you want the gauge to know it is fully charged before the charger stops charging, otherwise the gauge will not work correctly.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 120 points

    Hi Wyatt,

    The taper current of the charger is currently set to 1A. How would you define the thresholds?

    Thanks,

    Van

  • 0 in reply to Van_Ng
    TI__Guru** 105600 points

    Hello Van,

    The gauge charge termination taper current should be higher than the chargers (atleast 10% higher), then just follow the steps outlined.

    Check section 3.7 to make sure the gauge will see when a charge termination condition is met: https://www.ti.com/lit/ug/sluubw5/sluubw5.pdf?ts=1595430438723&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ34Z100-G1

    Sincerely,

    Wyatt Keller