• State TI Thinks Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 188 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ27426: Battery level does not drop below 10%

Kazuya Nakai59
Guru 21535 points
Part Number: BQ27426

Tool/software:

Hello guys,

One of my customers uses BQ27426 for battery in their current product.

They faced a trouble that the battery level does not drop below 10% at this moment.
This trouble was observed on only one unit of a few hundred.
The customer wanted TI to check whether their circuit has any bad point or not.
But they don't want to disclose their circuit on this site.

So I want to ask TI to check the customer circuit off line.

Could you please give me your reply?

Your reply would be much appreciated.

Best regards,
Kazuya.

  • 0
    TI__Mastermind 24751 points

    Hello, 

    How did you match the ChemID for this application? Also was a learning cycle successfully completed? 

    Regards, 

    Robert. 

  • 0 in reply to Jonny
    Guru 21535 points

    Hello Robert,

    Thank you very much for your reply.

    And I'm sorry that my explanation about the customer's trouble was not correct.

    Correct explanation about the trouble is below.

    [Trouble]
    At one unit of one thousand units, the BQ27426YZFR Voltage(), state-of-charge,
    and AverageCurrent() can not be updated.

    [Related information]
    - This trouble was occurred when they turned BQ27426 on the first time.
    - Regardless charging and discharging, the state-of-charge is not changed from 9%.
    - Voltage() and AverageCurrent() also do not change.
    - The trouble was resolved by battery pack removing from BQ27426 and re-attaching to BQ27426.
    - They use BQ27426YZFR and BQ24296MRGER together.
    These devices are connected to same I2C bus.
    They think the I2C bus is no problem because the BQ24296MRGER REG08
    CHRG_STAT is updated correctly.
    - Powering from the battery and charging to the battery by BQ24296MRGER
    are possible without any problems.

    Are there any possible cause of this trouble?

    Thank you again and best regards,
    Kazuya.

  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 24751 points

    Hello, 

    Had they programmed their configuration onto the gauge before this? 

    Regards, 

    Robert. 

  • 0 in reply to Jonny
    Guru 21535 points

    Hello Jonny, Robert,

    Thank you very much for your reply.

    I'm sorry to bother you. I asked them again what the problem they found is.

    [Problem]

    BQ27426 did not work properly the first time it was turned on.
    After that, I removed the battery and put it back in and it worked properly.
    It has continued to work normally since then.

    In this case, what do you think could be the cause of the malfunction which occurred on first power on timing?

    Your reply would be much appreciated.

    Best regards,
    Kazuya.

  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 24751 points

    Hello, 

    This is a ROM gauge, meaning that every time the gauge is restarted or POR, the gauge loses it's configuration. So every time the battery is removed or the gauge is power cycled or the gauge is restarted, you must use the host MCU to reprogram the custom configuration onto the gauge otherwise you will just be using the default parameters. Please ensure that this has been done. 

    Regards, 

    Jonny. 

  • 0 in reply to Jonny
    Guru 21535 points

    Hello Jonny,

    Thank you very much for your reply.

    Yes. They write the customer configuration every battery attaching.
    As I wrote phenomenon which they faced at the first portion of this thread. 

    Some of the phenomenon are the below.

    - Regardless charging and discharging, the state-of-charge is not changed from 9%.
    - Voltage() and AverageCurrent() also do not change.

    If BQ27426 uses the default parameters, will these phenomenon be occurred?

    Thank you again and best regards,
    Kazuya. 

  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 24751 points

    Hello, 

    You must do a couple of things before you can expect the SOC to behave accurately: 

    • You must match the chemID you are using by using the GPCCHEM tool. 
    • You must successfully complete the learning cycle. 
    • You must create the golden image and program this onto the gauge every time it is power cycled or restarted, otherwise the gauge will use the default configuration (which is likely vastly different from your configuration). 

    If any of these steps are skipped then you cannot expect the SOC to behave accurately. So please ensure you have done all of this.

    Regards, 

    Jonny.