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BQ40Z50-R1: battery SOC related DoD0 definition

Billy Liao
Prodigy 20 points
Part Number: BQ40Z50-R1

Hello,

I'm using BQ40z50-R1 EVM to get 4-cell individual SOC information for battery balance, and I tried to read IIii to LLll (DOD0  cell 1 to 3) in ManufacturerAccess() 0x0074 GaugeStatus2. 

Therefore, I can exactly know battery capacity SOC(1-DOD) instead of voltage if battery is LiFePo4. But I noticed the value is fixed (no change) on the GUI when 4-cell battery charging ,discharging and balancing.

There are some questions :

1. Supposedly DOD0 will change  when using Impedance Track™,or DOD0 is just a parameter ?  

    Can I use DOD0 value to determine battery capacity ?

2. If could, what's setting or condition I missing ?

3. If couldn't, do we have 4 cells individual SOC solution (like voltage,temperature)instead of totally battery pack SOC ?

4. Could I say 1-DOD = SOC ?

Please help me on this.

Thank you. 

Best Regards,

Billy

  • 0
    TI__Guru 73830 points
    The DOD values do not update very often. They typically only update when the cells are at rest and the voltages have stabilized to the point where they are changing at less than a 4uV/s rate. They are checked every 100s when at rest. The DOD points do not change when the pack is charging or discharging, although they can get set at charge termination. The DOD points are used for various features such as Qmax updates, setting the cell balancing time, etc.
  • 0 in reply to ThomasCosby
    Prodigy 20 points
    Hello Thomas,

    Thank you for reply.

    How could bq40z50-r1 know instantaneously DOD values when cell balance (CB (Bit 0): Cell balancing 1 = Cell balancing enabled) if DOD0 values do not update very often? It uses Cell1-4 Bal DOD ?
    if yes, could you tell me where can i get Bal DOD information ? ( register) I can't find it on Technical Reference.

    Thank you.