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Original question:

Gas gauge algorithm

BQ40Z50: update of FCC and RC of gauge

liting Lei
Intellectual 325 points
Part Number: BQ40Z50
Other Parts Discussed in Thread: BQ2084-V143,

 slua450 application note outlines  RM and FCC update take place after each resistance grid-point update, at the end of discharge, and at the exit of relaxation mode.

Not understand clearly.

For RM,  as known, RM is updated continuously every 1 second. not only at above timeline.

For FCC, FCC=Qstart+passedcharge+RM. Qstart can be abtained in a relaxed state. passedcharge and RM are updated every 1 second. if that, FCC is also can be updated every 1 second.

in addition, Qstart=Qmax*(DOD0-DODcharge), To ensure FCC update take place, Qmax should should be upate first, right?

Qmax update can occur at charge or discharge event. So FCC update can occur after charge or discharge, right?

please help on above question, thanks,

  • 0
    TI__Mastermind 42535 points
    FCC will not be updated every second. It will only be updated when IT simulations are done.
    Yes, it can occur at grid points during dsg, or at end of charge.
  • 0 in reply to Batt
    Intellectual 325 points
    Could you input more information about IT simulation? which is it refer to? RM simulation, FCC simulation or voltage simulaton?
    RM and FCC update take place after each resistance grid-point update, at the end of discharge, and at the exit of relaxation mode.
    1. FCC update after each grid -point, so FCC can update for several times for the whole discharge process?
    2. At the exit of relaxation mode, which scenario belongs to this mode?
    3. My question is very simple? how does it update during the normal run? could you please list the conditons before FCC update?
  • 0 in reply to liting Lei
    Intellectual 325 points
    For previous Gauge BQ2084, The bq2084-V143 updates FCC with an amount based on the value in DCR if a qualified discharge occurs.
    A qualified discharge occurs if the battery discharges from RM = FCC - Near Full to the EDV2 voltage threshold
    with the following conditions:
    · No more than 256 mAh of self-discharge or battery load estimation occurs during the discharge period.
    · The temperature does not drop below the low temperature threshold programmed in Learning Low Temp DF
    0xac during the discharge period.
    · The battery voltage reaches the EDV2 threshold during the discharge period, and the voltage is greater than
    or equal to the EDV2 threshold minus 256 mV when the bq2084-V143 detects EDV2.
    · No midrange voltage correction occurs during the discharge period.
    · Current remains £ 3C/32 when EDV2 or Battery Low % level is reached.
    · No overload condition exists when EDV2 threshold is reached, or if RM() has dropped to Battery Low% x
    FCC,
    · No valid charge activity occurs during the discharge period. A valid charge is defined as an uninterrupted
    charge of 10 mAh into the battery

    For impedance tracking gauge, what conditions included before FCC update.
  • 0 in reply to liting Lei
    Intellectual 325 points

    is there anyone can help on this question? thanks,

  • 0 in reply to liting Lei
    Intellectual 325 points

    who can help on this question? thanks

  • 0 in reply to liting Lei
    TI__Mastermind 42535 points

    You are mistaking a CEDV gauge with an IT gauge. An IT gauge does both coulomb counting as seen by RM decrease every second or so when you dsg and also take IT measurements along the dsg at grid points and during relaxation.
    For the bq40z50
    1. FCC can update at grid points (these are points where resistance is calculated and IT simulations happen) and also during relaxation and entry into chg/dsg.
    2. At exit of relaxation you enter either chg or dsg mode at which point if dsg, then your load select and load mode determine the load value of current that will be used by IT for FCC estimation.

    The above 2 cases explain FCC estimation in IT gauges.