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Balance Time values BQ40Z50 always zero

Ymif Engineering
Prodigy 50 points
Other Parts Discussed in Thread: BQ40Z50

Hello,


I'm using the BQ40Z50 with a 4 cell configuration.

I want to use the intern balance option so the function is enabled in the register.

I tried al lot of settings but the four belance timers always says zero, so the BQ40Z50 will never balance the cells.

The cells are enough out of balance.

  • 0
    TI__Guru 73830 points

    Rick,

    Does Update Status = 0E. Cell balancing is inhibited until a field Qmax update has occurred. Reference page 54 of the TRM.

    Tom

  • 0 in reply to ThomasCosby
    Prodigy 50 points
    Hello Tom,

    Update Status = 04
    I have cycled the battery pack more then ten times.
    Qmax wil never be updated.

    Rick
  • 0 in reply to ThomasCosby
    Prodigy 50 points

    Hello Tom,

    I have checked some registers.
    One thing what I have seen is the CF bit is set in de gauging status register.
    Is that the reason why Qmax and Ra will not update?

    The TRM explains the CF bit that a conditioning cycle is needed.
    What does it mean? A complete discharge en charge?
    Last night I have cycled the battery pack, but the CF bit is still set.

    Second thing is that the Max error is 100%. That's not OK

    What should I do?

    Rick

  • 0 in reply to Ymif Engineering
    Prodigy 80 points
    I just use this chip recently ,
    your pack has no Ra-table update nor Qmax update for Update status=04, I try to give you some advice to learning the pack,
    1. Make sure the chemical ID is matched the cell
    2. Make sure Gauge_EN bit is set in manufacturing status ( IT enable command should be sent)
    3.Charge the pack to full and rest 5hours or REST bit set in Gauging status
    4.1/5C discharge to empty and rest 5hours or REST bit set
    5.repeat step3 and step 4
    Then the update status could be updated to 0e if go well, and the balancing time should be updated after that.
  • 0 in reply to Xijun Fan
    TI__Guru 73830 points

    Update Status should equal to 06 after those steps. Another Qmax update is required to bump it up to 0E. You should check the Update Status after the first time that you reach Step 4. It should be 05. The Ra Table should update on the second loop through Step 4 and Update Status should equal 06. It should bump to 0E after charging and resting again. I recommend logging data through the entire process so that we can analyze any problems that may occur. It Update Status does not increase to 05, then stop and send the data to me.

  • 0 in reply to Ymif Engineering
    TI__Guru 73830 points
    The CF flag will be set until Qmax is update. It may also stay set until the optimization cycle has completed.
  • 0 in reply to ThomasCosby
    Prodigy 50 points
    I have tried the points wich are mentioned above.
    It seems to work well.
  • 0 in reply to Ymif Engineering
    Prodigy 50 points
    Hello,

    I have a second problem with the BQ.

    It seems the balancing circuit is working.
    But I have trouble with the SOC.
    I have tested the battery pack multiple times.

    Last weekend, the battery pack on my desk located without load. On friday the SOC was 100%.
    Now on Monday soc has dropped to 32%. I have two battery packs, both have the same problem.

    Whats wrong?

    Rick
  • 0 in reply to Ymif Engineering
    TI__Guru 73830 points
    The DOD point would have timed out after 48 hours and the gauge will reset it. FCC, RM and SOC could have been downgraded due the the cell voltages. Have would verified that the ChemID is a good match for your cells? Have you run the optimization cycle? These could contribute to error in these simulations.