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[BQ27510] WAIT_Id on Flags registers

Victorien v
Intellectual 520 points
Other Parts Discussed in Thread: BQ27510

Hello,

I used a fuelgauge BQ27510 to monitored a battery. I created the golden pack and it work correctly.

but when I control the fuelgauge with "bq evaluation software", the WAIT_ID bit on flag register is always active.  In the datasheet, there is no information about it.

Is there someone who know how this flag work ?

 

thinks for help

 

  • 0
    TI__Intellectual 2100 points

    Victorien,

    This flag is for really used for information only. 

    The bq27510 is a host-side gauge that holds two pack profiles in its memory (pack0 and pack1).This way, the gauge can accurately determine the cell characteristics even when the user swaps an old/empty battery for a new cell.

    Imagine that a user has cell A and cell B.  If the user has been using cell A, then the gauge will be continually learning information about this cell in the pack0 profile.  When the user swaps cell A for cell B, then the gauge detects that a new cell has been inserted, and begins learning about cell B in the pack1 profile, while keeping all of the information about cell A in its memory under the pack0 profile.  If cell A is then re-inserted at a later time, then the gauge detects the original cell and uses the pack0 profile.

    This works by matching measured cell voltage/current to each profile in memory.

    Unfortunately, when you initially insert the cell, the gauge does not have enough information to determine which cell is connected, as it only sees a voltage.  The gauge can only determine which cell is attached when a load is applied.

    The WAIT_ID bit means that the gauge has NOT determined whether is using the pack0 or pack1 profile in memory.  This generally means that a significant enough load has not been pulled to determine this value.

    Note that if your application operates at light load (roughly <= C/10), then since the load is so light, then you will not be able to determine which profile you are using at any point. However, this is not a problem.  At light load, the most critical information is contained in the OCV curve, which is constant.

    The pack profiles are of the battery impedance.  At such a light load, it is irrelevant which profile you are using since the voltage drop is negligible.

    Let me know if this helps,

    Charles