• State TI Thinks Resolved
  • Locked Locked
  • Replies 9 replies
  • Answers 2 answers
  • Subscribers 64 subscribers
  • Views 466 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.

BQ40Z80: Bq40z80 Unstability at low SOC

z4ci4n
Prodigy 80 points
Part Number: BQ40Z80
Other Parts Discussed in Thread: BQ34Z100

Hi TI expert,

I am using Bq40z80 to control 7-Series battery. I know the problem with the 7th cell measurement. I did so many test and realised that 7th cell measurement is not that bad. (Max. 5mV deviation)

When the RSOC is %0 IC has an interesting behaviour. For example; DFET and CFET begins to ON OFF, at the same time communication is intermittent.

Please give me some suggestions to solve this problem. ( Except choosing an another IC to control 7-series battery because I dont have that chance)

Thanks in advance

  • 0
    TI__Guru** 105760 points

    Hello,

    The bq40z80 doesn't support 7S system anymore. This is one of the issues that occurs randomly with 7S systems, you will need to use a top of stack gauge like bq34z100 with a monitor.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 80 points

    Hi Wyatt,

    Thanks for your answer.

    Unfortunately it is too late to change my design. Its easy for you to tell me use a different IC but its not that easy for people who are currently using this IC to control 7-series Battery. Please tell me how can I solve this problem without changing my design.

    Thanks in advance

  • 0 in reply to Wyatt Keller
    Expert 1186 points
    Hi  Keller,

               Oh, my God, I also encountered a similar problem. The 7S battery cannot be charged and waked up after shutdown. Now the project is ready for mass production. I think it is the same problem.

                I also hope to solve this problem.

  • 0 in reply to jmyang
    TI__Guru** 105760 points

    Hello,

    The bq40z80 was changed for only 6S support because of similar issues. I will have to check our timeline for releasing new FW that may help with some of the issues, but it will still not be rated for 7S.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Expert 1186 points

    Hi  Keller,

          Can the new firmware solve the problem of not being able to wake up after shutting down?

          When will the new firmware be released？

          We can accept the inaccuracy of the 7S voltage.

           In order to solve the problem of not being able to wake up after shutdown, we tried to reduce the shutdown voltage from 2.75V to 2.3V. It seems that it can wake up at 2.3V. Is this a good solution?

           

          

  • 0 in reply to jmyang
    TI__Guru** 105760 points

    Hello,

    The timeline is sometime in the first or second quarter 2021, this is not confirmed though.

    It sounds like your shutdown voltage threshold was set too high, reducing the threshold can help make it easier.

    Sincerely,

    Wyatt Keller 

  • 0 in reply to Wyatt Keller
    Prodigy 80 points

    Hi Keller,

    Thanks for your answer again.

    As I mentioned before we need a solution for 7-series battery. Why the new fw that will solve some problems will not be rated for 7 series? There are lot of people like me who use this IC to control 7S. We want TI to release a fw that will solve problems and keep supporting 7S.

    Thanks in advance.

  • 0 in reply to Wyatt Keller
    Prodigy 80 points

    Hi Keller,

    We are waiting for your answer.

    Thanks.

  • 0 in reply to z4ci4n
    TI__Guru** 105760 points

    Hello,

    The bq40z80 will not be re-specified for 7S support after the FW release. It will only help fix the existing issues with it's operation in 7S configuration.

    Sincerely,

    Wyatt Keller