• State TI Thinks Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 3 answers
  • Subscribers 64 subscribers
  • Views 1450 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.

BQ40Z50-R2: Questions about learning cycle

Duoduo Cheng
Expert 3050 points
Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQ40Z50, BQ40Z80, BQSTUDIO

1. In step 7, is there some requirement about the charging current for  the battery. I see 0.5C in some materials, but our fast charge is designed to be 1C. And the battery specification also requires 1C. Does this have effect on learning?

2. In step 11, if the result of update status is already 0x0E after step 10. So is there no need to do step 11.

3. When I used bq40z50-R2 to do chemid learning, the update status is already 0x05, and qmax is updated, and, before learning cycle, do I need to change the update status to 0x04 manually?

4. After the product shipped, does it need to enable the update status (Bit 2): Impedance Track gauging and lifetime updating? Manually setting update status = 02 above means shutting down the IT algorithm? But I remember that someone in forum said that after the senc file was burned to the new IC, calibration, testing and GAUGE_EN are still needed. Does it mean that the update status is changed to 04 again?  So what is the purpose of manually changing update status to 02?

  • 0
    TI__Expert 4645 points
    Below are comments/answers to your questions:
    1. 0.5C is recommended, but using 1C charging will not affect the results for learning. I have recently published an updated learning cycle app note specifically for the bq40z80, but it also applies to the bq40z50, and can be viewed at www.ti.com/.../slua848.

    2. I can't read the initial instructions in Chinese, so I am not sure what recommendations were made prior to this. If you reach 0E in on charge relax discharge relax cycle, then you are not starting from LStatus() = 00 or 02.

    3. To do a full learning cycle, set the LStatus() to 02 to ensure that the updates are tracked correctly and you know that a learning cycle has been completed.

    4. After doing the learning cycle, the LStatus() is set to 2 to ensure that when the pack is assembled and gauging and lifetime data is enabled later, the cycle counts start from 0.
  • 0 in reply to Steve Schnier
    Prodigy 150 points
    Steve, in reference to your answer point 2. and 3. the LStatus 00 or 02 is different to what should be verified for LStatus = 04 in SLUA848, chapter 4.2.1 last bullet point.
    I check LStatus = 04 as a start requirement in my custom learning cycle software, can you please confirm the correct number?
  • 0 in reply to Mictronics
    TI__Expert 4645 points
    If LStatus is 00b, then a QMax and resistance table has never been updated in a learning cycle, so another run will be ok for a learning cycle. Either LStatus 0 or 2 is ok to do another learning cycle. The first time through will be LStatus = 0.
    After discharge and rest, IT must be enabled, so that would be LStatus of 04.
  • 0 in reply to Steve Schnier
    Prodigy 150 points
    Thanks Steve. So, I started and run a first learning cycle from LStatus = 0x04. First discharge passed, relax took 5 hours (RDIS was still set at the end). Then the charge task started and after some time the CHG FET turned off and OC flag was set.

    My guess is a default/wrong parameter setting or it's due to the fact that this BQ40Z80 was used already for GPC cycle with a single cell and has seen charge and discharge.
    However, I cannot reset the chip to factory defaults since the firmware is not yet released.

    Any ideas on the OC flag problem?

    Unfortunately I cannot run BQStudio and my learning cycle software at the same time because I have only one EV2300. So providing logs is a problem.
  • 0 in reply to Mictronics
    Prodigy 150 points
    So the reason for over charge seems to be the fact that I already get an RSOC of 100% (Max error also 100%). I disabled OC protection for now to keep charging.

    For the RDIS not being cleared, possible that 5 hours relax are to short for a 10Ah 6S pack? By then it seems the voltage still not meets the criteria of <4uV/s for OCV reading.

    And one more detail to confirm: GPC cycle for chemistry ID can be done with a single cell, running the entire pack is not required, right? At least that's what I found here in the forum.
  • 0 in reply to Mictronics
    Prodigy 150 points
    Finally run a complete learning cycle that passed all flags and LStatus requirements. Before this one I re-programmed the chem ID, here in forum it was said after that a new learning cycle is required. Obviously a few parameters were reset and that helped to pass the new learning cycle. LStatus is 0x06 now and I will run another cycle for field update to 0x0e. Max error is showing 1%, Qmax for each cell indicates 10.5Ah, an expected value.

    Anyway, thanks again Steve for you support.