• State TI Thinks Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 1 answer
  • Subscribers 65 subscribers
  • Views 179 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

BQ20Z80: Full Charge Capacity Update

Michael Buergo
Prodigy 10 points
Part Number: BQ20Z80

Hello,

I am looking to see if there is a clear indicator in the data flash that will provide notice that Full Charge Capacity is going to update. 

Also, there is this note in the SLUA364, Does this mean that the FCC will only update after 20 cycles?

Thanks,

Mike B

  • 0
    Prodigy 10 points

    What is prompting this question is that I would expect my Full Charge Capacity to be close to Qmax pack - reserve capacity after a Charge → Relax 2 Hour → Discharge → Relax 5 Hour.

    In my case the Qmax is being updated to 6350 mAh, Reserve Capacity is 330 mAh and I am getting about 5400 mAh for FCC. The cells are new and when a capacity test is run, I can consistently get >90% of target capacity of 6300 mAh. Cells used are US18650VTC4 in a 3P4S configuration.

  • 0 in reply to Michael Buergo
    TI__Guru 56496 points

    The gauge doesn't have a flag that indicates an FCC update. There are many reasons for FCC updates (e.g. full charge, full discharge, state change (relax/discharge/charge), significant temperature change, significant DOD change etc.

    The Max Error info doesn't control FCC updates. There is no 20 cycles requirement for an FCC update.

  • 0 in reply to Dominik Hartl11
    Prodigy 10 points

    Are Update Status and MaxError not indicators of different updates happening in the GG?

  • 0 in reply to Michael Buergo
    TI__Mastermind 35221 points

    Hey Michael,

    Dominik is currently out of office, he should get back to you later this week.

    Regards,

    Nick Richards

  • 0 in reply to Michael Buergo
    TI__Guru 56496 points

    Yes, Update Status indicates if the gauge updated the cell resistance tables and Qmax, during a learning cycle or regular use. MaxError indicates an expected margin of error. Neither are direct indicators for FCC updates. FCC updates every time the gauge performs a capacity simulation so that's way more often than Update Status or MaxError change.

  • 0 in reply to Dominik Hartl11
    Prodigy 10 points

    Hi Dominik,

    Thanks for the reply.

    I am trying to understand why my company records FCC prior to any pack conditioning. We receive battery packs from our supplier without any electrical tests or charge/discharge cycles performed on the pack. Our test procedure for the pack measures and records the FCC value before the pack is conditioned. I think this value will be inaccurate. I am proposing moving this measurement step until after the pack goes through:

    1. Charge → Relax 2 hours or,
    2. Charge → Relax 2 Hours → Discharge → Relax

    Thanks,

    Mike Buergo

  • 0 in reply to Michael Buergo
    TI__Guru 56496 points

    The basic flow recommended for TI gauges is:

    1. Develop and verify a configuration that works for a new battery. The result is a Golden Image, which configures to gauge to work with this make/model battery and application. As every battery is slightly different, this is intended as a good starting point. The gauge will then adjust to the actual battery during regular use (which means that there will be a slight error at the beginning).

    2. In production, program the Golden Image. This is good enough for a functional test.

    3. If you want to test for best performance, let the gauge learn Qmax and Ra (which is indicated with Update Status). After both Ra and Qmax are updated in the field, run a performance test.