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Load Select - Current Discharge Cycle

Other Parts Discussed in Thread: BQ27510-G1

According to the BQ27510-G1 datasheet, when Load Mode = 0, and Load Select = 1, the present average discharge current from the beginning of the current cycle to present time is used to determine load-compensated capacity.  Is there a command that can be used to obtain this average cycle discharge current similar to the AverageCurrent() command?

Thanks,

Anthony

  • To add onto this I had some additional questions.

    1. A resistance update is determined by the following equation according the Single Gas Gauge Application Book:
    R(DOD) = dV/I
    Is "I" in this case the instantaneous current that is measured (I.e. AverageCurrent()) or is the the current dictated by the LoadSelect option?

    2. With regards to Load Select = 1, how is a discharge cycle defined? In addition, for this discharge cycle, does this take into account the current during both discharge mode and the relaxation mode?

    3. How is a Qmax update related to an FCC update. Are these parameters always updated at the same time? Also, do these parameters use the OCV reading to make an update?

    4. FCC updates have been observed when our system exits from a relaxed state to discharge mode. Can I assume that an OCV reading is taken the moment right before the system enters discharge mode?

    Thanks,
    Anthony
  • Hi Anthony,

    If the command isn't listed in the TRM -technical reference Manual, it isn't there. The closest thing to that is "the Avg I Last Run" in data flash, but there isn't an exact command to do what you seek.

    1.  This is the Averagecurrent()

    2. pls refer to app note SLUA364. it describes the various modes of the battery, namely relax , charge and discharge modes. This will be current greater than the discharge current threshold.

    3.Refer to SLUA364. It explains in detail the IT algorithm. Qmax requires two rest periods. FCC updates occurs when ever there is a rem cap simulation. This occurs at start of charge, start of discharge, at the resistance grid points, when ever the temperature changes by more than 5 degs and a few other instances. refer to the app note for details.

    4. Again refer to app note SLUA364. Search for this app note on ti.com. The fact that you have an FCC update doesn't necessarily mean than an OCV measurement was taken. OCV- stands for open circuit voltage, meaning the battery is not under load. If there is  current flowing which is  below the quit current (refer to that app note) the OCV measurement will be corrected for for the IR drop due to that current. The app note describes when OCV measurements are taken.

    thanks

    Onyx

  • Hi Onyx,

    Thanks for your reply. With regards to your answer to item #2, I understand discharge mode is based on the Discharge Current Threshold and Quit Relax Time.  However, it is still unclear how the fuel gauge determines the value of the average discharge current for a given cycle using Load Mode = 0 and Load Select = 1.  Does this value only take into account the battery current during discharge mode or is the battery current during relaxation mode (i.e. current below the discharge current threshold and current above discharge current threshold but below the quit relax time) taken into account as well?

    Anthony

  • HI Anthony,
    I had to have the code looked into to be able to say definitely. It takes into account the battery current which is above quit current. So my previous response should have been current greater than the quit current and not the discharge current threshold.

    thanks
    Onyx