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BQ20Z40-R1: Unable to complete Learning cycle as UpdateStatus does not equal 0x06 (it is 0x0D)

Jeremy Heath
Prodigy 30 points
Part Number: BQ20Z40-R1

Tool/software:

I have completed a couple of cycles but they always end with UpdateStauts as 0x0D. I do not expect UpdateStauts to be greater than 0x06 according to the TRM pg 151.

I do see the RDIS flag clearing after first discharge.
During Charging, the FC flag is set
During Discharging, the FD flag is set
I do see the VOK flag clearing during the rest after Charging and Discharging.

A capacity is learned that is different than the nominal. I see the Qmax change from 1050mAh (nominal) to around 1030-1060mAh

CHEMID: 7539
The pack is a 2S1P
Cell is RouteJade SLPB593459HP1

Charge Parameters
8.4V, 525mA taper is 50mA
Discharging Parameters
5.4V 210mA or 150mA

I can provide logs.

  • 0
    TI__Guru 61856 points

    The relevant bits in update status for a learning cycle are bits 0 and 1. If you read 0x0D, mask this with 0x03 and you get 0x01. So your update status is actually 0x01 for learning cycle purposes.

    This means that the gauge learned Qmax (which is good as this is usually the tricky part for a learning cycle).

    Please make sure that you start the discharge *after* update status & 0x03 is 0x01 (after Qmax has updated). Also make sure that the load is above C/10 (e.g. C/5) during the discharge and that RDIS is 0 all the way during the discharge.

  • 0 in reply to Dominik Hartl11
    Prodigy 30 points

    For confirmation, This result would indicate that the Qmax was learned (Qmax nom is 1050). Does this indicate a successful Learning Cycle?

    Qmax Cell 0 = 1111
    Qmax Cell 1 = 1114
    Qmax Pack = 1111
    Update Status = 0D
    Cell 0 Chg dod at EoC = 288
    Cell 1 Chg dod at EoC = 352

    (cell 2,3 not used)

  • 0 in reply to Jeremy Heath
    TI__Guru 61856 points

    This indicates that the gauge completed the first part of the learning cycle successfully. But it didn't update cell resistance. The cell resistance update will happen if you discharge at a rate that's higher than C/10 (e.g. C/5) and the ChemID is compatible (RDIS never gets set).

  • 0 in reply to Dominik Hartl11
    Prodigy 30 points

    One more Charge to FC bit =1, I got the following DataFlash where Update Status = 0xE.  I believe this is equivalent to 0x6, is this correct?

    [State(Gas Gauging)]
    Qmax Cell 0 = 1061
    Qmax Cell 1 = 1062
    Qmax Pack = 1061
    Update Status = 0E
    Cell 0 Chg dod at EoC = 16
    Cell 1 Chg dod at EoC = 16

  • +1 in reply to Jeremy Heath
    TI__Guru 61856 points

    0x0E means that the learning cycle has completed. The only relevant bits are bits 0:1 (assuming that the IT algorithm is enabled, which is indicated by bit 2). So 0x0E is the equivalent 0x06 and 0x02 as 0x0E & 0x03 and 0x06 & 0x03 = 0x02.