• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Subscribers 63 subscribers
  • Views 1020 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 Overcharge Trip

TcPaden
Expert 1085 points

While trying to run a learning cycle, I got an OverCharge trip, which turned off the Chg FET and halted the charging (gotta turn off Protections for learning cycles!).

What I don't understand is why:

RemainingCapacity() = 4738 mAh
FullChargeCapacity() = 4826 mAh
OC:Threshold = 300 mAh

The definition for an OC Trip is when RemainingCapacity() => FullChargeCapacity() AND internal charge counter => OC:Threshold

Why did it trip?

Thanks.

Tom

  • 0
    TI__Guru 73830 points
    Tom
    Is RSOCL set? If so, RM will be held at 99% and the internal charge will continue to accumulate and can result in an OC fault.
    Tom
  • 0 in reply to ThomasCosby
    Expert 1085 points
    Tom,
    RSOCL = 0. But I looked through the log file and saw that RemCap came up and exceeded FullChgCap, setting the flag. I guess it drifted before I checked it long after the trip occurred.

    What I don't understand now is why is SafetyAlert[OC] still set?
    Tom
  • 0 in reply to TcPaden
    Expert 1085 points

    2015-04-07 OPT326505A Learning Cycle.xlsx

    After looking at the log file again, I may have found a firmware bug.

    The data sheet says that when RemCap => FullChgCap: 
         SafetyAlert[OC] = 1

    If that condition continues, when the Internal Charge Counter => OC:Threshold, then:
         SafetyAlert[OC] = 0
         SafetyStatus[OC] = 1
         OpStatus[XCHG] = 1 (which disables the CHG FET)

    From my log file, it looks like XCHG is set while SafetyAlert[OC] is still 1, and SafetyStatus[OC] never gets set?

    The log file is attached. I've highlighted the cells where the SafetyAlert[OC] was set in light gray, and where the charge current went to 0 in red.

    Is this a bug or am I reading something wrong?


    Thanks.

    Tom

  • 0 in reply to TcPaden
    TI__Guru 73830 points
    The CHG FET was opened due to a COV event. There has only been 165mAh of charge accumulated since RemCap = FCC, so this may not have been enough charge to trigger the OC Safety Status event.
  • 0 in reply to ThomasCosby
    Expert 1085 points
    I see it now. The COV happened faster than the log file update rate, so the COV Alert going active was missed in the log file, and I focused on the OC instead.

    Once again, thanks for the help!