• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Subscribers 64 subscribers
  • Views 254 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.

Original question:

BQ34Z100-G1: Which DataFlash parameters control when SoC gets re-measured based on OCV (etc.)?

BQ34Z100-G1: Should FCC be updating DURING a charging cycle?

Kevin Banks
Prodigy 235 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQ34Z100, BQSTUDIO

While monitoring a long recharge cycle today, I noticed that the BQ34Z100 was updating FCC along the way.

I had gotten the impression from the docs that a new FCC would not be recalculated until the end of the charging cycle.

1. Is it normal for the FCC to be updated WHILE the battery is charging?

2. Or does this indicate that the gauge is incorrectly triggering a Valid Charge Termination (VCT) Event WHILE the battery is actually still charging?

  • 0
    TI__Genius 10370 points

    Kevin,

    The FCC parameter will update FCC if the device is full and you have not reached VCT. It means you are underestimating capacity so it adjust FCC upwards. If you are in the. 

    Normally yes FCC does not update in Charge like it does in Discharge. Let me clarify True FCC is updating more frequently in discharge. 

    Thanks,

    Eric Vos

  • 0 in reply to Vos
    Prodigy 235 points

    Let me try to restate your answer and you tell me if I am correct:

    If enough incoming charge (coulomb counting) comes in, the gauge can update FCC while a charge cycle is still in progress.

    To make my question more concrete, here are some actual readings reported by BQStudio today (as the charge cycle was running)

    (Design Capacity - DC is 15.2AmpHours)

    Time SOC FCC RC

    8:33 1% 15.052 0.100 (battery had been discharging over the weekend)

    9:33 15% 15.090 2.125

    10:38 29% 15.132 4.267

    11:36 41% 15.169 6.215

    13:06 61% 15.226 9.209

    14:06 74% 15.265 11.213

    So the battery is not "full" (yet) but FCC has been getting adjusted upwards (small adjustments).

    Is it normal for FCC to be getting adjusted before RC reaches FCC?

    (It makes sense that if RC started to go ABOVE FCC that the gauge would raise FCC)

  • 0 in reply to Kevin Banks
    TI__Genius 10370 points

    Kevin,

    Are you able to provide a log file? ideally one recorded from bqStudio?

    Thanks,

    Eric Vos

  • 0 in reply to Vos
    Prodigy 235 points

    Yes I will try to capture a log file using BQStudio and provide in a few days.

    Update: I can see these log files growing very large - how long of a time span do you want to examine?

    (This battery pack takes many hours to fully recharge)

    Update: I see under the Insert menu of this forum that you can Insert a Video/Image/File, but it won't accept my log file.

    Is there a size limit? Is there a permission issue?

    Note that the file was just a test log, made while the battery is currently discharging...

  • 0 in reply to Kevin Banks
    TI__Guru** 105590 points

    Hello Kevin,

    Sorry for the late response.

    You can set the sample rate if your logs will take days to complete. That is the correct place to upload files, it may be too big to upload.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 235 points

    What we found: the "Charge Voltage" parameters had been set too high, so the gauge never considered "end of charging" to be reached.

    With these reduced to a voltage threshold that WAS reached at the end of the cycle, the gauge "jumped" it's estimate up to 100% at the end of the charging cycle.

    The gauge seems to be computing reasonable values for FCC, so the details of WHEN it chooses to update FCC are no longer important.