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bq40z50, VCT (Valid Charge Termination) 40s Condition

R B
Prodigy 140 points

Dear all :

 Good day~ 

VCT condition check as below :

All of the following conditions must occur for two consecutive 40-s periods

(@4.6 of SLUUA43.pdf, page 33 / Version December 2013)

this is the last condition I've checked (AverageCurrent() < Charge Term Taper) .

----- Data log as below----

 _01_Initial.rar

-----

 

@18613, start to charge and RSOC = 0%

@22101, AverageCurrent < 100mA, [ VCT setting (I,V)=(100mA,75mV) ]

@22149, TC/FC SET and charger stop charging, RSOC = 100% [CHGFET=1]

 

Q1 :

Two consecutive 40-s periods is mean 40sec+40sec=80sec?

But 22101-22149=48 sec only in data log.

 

 

 

 

 

 

 

  • 0
    Prodigy 140 points

    Update：VCT condition  as below
    (@4.6 of SLUUA43.pdf, page 33 / Version December 2013)


  • 0 in reply to R B
    TI__Guru 73830 points
    It does not look like the pack rest period was long enough for the cells to stabilize. Was there a question in the second entry?
  • 0 in reply to ThomasCosby
    Prodigy 140 points
    Hi Tom
    Good day~

    "long enough for the cells to stabilize" is mean the pack status before charge?
    - The pack is REST before start charge. ( ITStat =0x0A11 @18414 )

    - Second entry is add VCT picture only for reference.

    Q1. Two consecutive 40-s periods is mean continue 80sec (40sec+40sec) ?


    Regard

    Robin
  • 0 in reply to R B
    TI__Guru 73830 points

    Yes, 80 seconds. I am not sure why it was defined that way.

  • 0 in reply to ThomasCosby
    Prodigy 140 points

    Hi Tom

    OK, got it.

    - We find RSOC go to 100% by VCT.
    But the total time of meet VCT condition as below
    --
    @22101, AverageCurrent < 100mA, [ VCT setting (I,V)=(100mA,75mV) ]
    @22149, TC/FC SET and charger stop charging, RSOC = 100% [CHGFET=1]
    --
    form sample 22101 to 22149 is "48 sec" only in data log, and FC/TC is SET.
    And "48 sec" is random...in 42 ~ 67 sec,  Why isn't it meet 80 sec condition?

  • 0 in reply to ThomasCosby
    Prodigy 140 points
    Hi Thomas

    May I know why isn't it meet 80 sec condition?

    or
    Need to change GG file setting to cover this?

    or
    TI need to check FW?
  • 0 in reply to R B
    TI__Guru 73830 points

    RB

    Let the pack rest longer. It has only rested for about 25 minutes in this log file and it typically takes 1 to 2 hours for the cells to rest enough for a Qmax update. You can zoom in on the voltage and see that it is still changing.

    Tom

  • 0 in reply to ThomasCosby
    Prodigy 140 points

    Hi Tom

    Thanks, I am double check data log again. REST bit and REST time is OK .

     

    I am check VCT condition as below

    Step-1. Check VCT bit SET at sample 22148, [ ChgStat =0x0088]

    Step-2. and check voltage and Average-Current before sample 22148.

    Step-3. Check delay time meet 40+40 sec or NOT?

  • 0 in reply to R B
    TI__Guru 73830 points
    RB
    The REST flag was set at the beginning of the log file, but we are looking for it to be set at the end of the file after the discharge. Have you allowed the pack to rest longer to see whether the REST flag will set?
    Tom
  • 0 in reply to ThomasCosby
    Prodigy 140 points

    Hi Tom

    the data log as below

    _01_Initial_All data.rar

    Step-1. discharge pack to empty and wait pack REST.

    Step-2. Charger start to charge pack until fully.

    Step-3. Check VCT condition.

  • 0 in reply to R B
    TI__Guru 73830 points
    RB
    It looks like you are making progress. The gauge did reach charge termination at sample 22149 and Qmax update at sample 40386.
    Tom
  • 0 in reply to ThomasCosby
    Prodigy 140 points

    Hi Tom

       Thanks, VCT condition is very clearly  after your guiding.

    one more question between sample 22101 and 22149.

    My customer is concern VCT trigger that is NOT meet 80 sec after Max cell voltage reach and AvgCurr < 100mA, (Term V, Term I)=(75mV, 100mA)

    So the <Two consecutive 40-s periods> is mean we need to wait 80sec or that is a range?

  • 0 in reply to R B
    TI__Guru 73830 points
    RB
    I checked your data at VCT and did not find exactly 80 seconds. The accumulated charge criteria normally occurs after the taper current criteria has been met. The intent for the requirement is to make sure the the charge current does not stop immediately after reaching the taper current. The gauge did continue to accumulate charge for 46 seconds before declaring VCT, but that would seem to be early. Anyway, it is easy to meet the charge accumulation criteria as long as you continue to charge after the taper current criteria has been met.
    Tom
  • 0 in reply to ThomasCosby
    Prodigy 140 points

    Hi Tom

      I got it about  <The accumulated change in capacity 0.25 mAh.>

    and last question as below :

    Q1. If the VCT bit set before 80 sec is OK?

    Q2. How to check the VCT function is right? (Now it not met TRM)