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BQ34Z100-G1: learning gauge bq34Z100-G1

micou ludovic
Expert 1215 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: GPCRB, GPCCHEM

Hello,

I use a BQ34Z100-G1. I would like to know how takes place the learning of the gauge? is it update the table Ra with regard to the current cycle or with regard to all the cycles seen by the battery?

I have a battery which undergoes a sequence cycle, will the table Ra be optimized at the end of the cyle?

The sequence is for all power (350W, 550W, 150W, 450W, 250W 350W) with many test of ambiante temperate for each power (the temperature is in the order that the cycle is realized : -30°C with 1h of heater, -30°C without heater, 20°C, -15°C with 1/2h of heater, 55°C, -15°C without heater, 0°C) 

When I compare the sequence at 350W -15°C without heater, with the sequence at 550W -15°C without heater, the test for 550W is bad for the remaining power. Can you give a explain for that? I join the result of the test and the *.gg.csv that I implement into the gauge.

Best Regards,

L.MICOU

file.rar

  • 0
    TI__Mastermind 25955 points
    Hi Micou,

    With regards to the learning cycle and Impedance Track based gauges:

    Yes, the gauge constantly learns and updates Qmax and the Ra tables if learning conditions are met. Typically, this requires a 37% DOD drop from a reseted state to another rested state. More information on learning cycles may be found in these app notes:

    www.ti.com/.../slua597
    www.ti.com/.../slua777

    However, the first learning cycle after programming a chemID is extremely critical and instead requires a 90% DOD drop (Assuming Li-Ion, 50% for NiMH, NiCd or PbA) from a rested state to another rested state. When performing the learning cycle (this first one) update status will update to 0x05 when Qmax has been learned and then to 0x06 when the Ra tables have been updated.


    With regards to the cells in cold temperature:

    Overall battery capacity is related to both load and temperature. Warmer cells tend to have a larger capacity than colder cells. At cold temperatures, cell impedance increases as temperature decreases.

    If you are experiencing SOC drops at cold temperature, to tune the parameters of the gauge for cold temperature performance, please utilize the GPCRB tool and supporting documentation found here:

    http://www.ti.com/tool/gpcrb

    Please let me know if your test results improve after utilizing the gpcrb tool.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Expert 1215 points
    Hi Kahler,

    The test result is obtain after I use the gpcrb tool.

    Best Regards,
    L.MICOU
  • 0 in reply to micou ludovic
    TI__Mastermind 25955 points
    Hi Micou,

    Thank you for the RAR included the graphs and gg.csv for your gauge.

    The values for design capacity and design energy look off. Could you please describe how you calculated them?

    Cell terminate is set at 2.714 V, is this correct?

    Before running the GPCRB tool, how did you determine the chemID for your cells? Please describe the steps undertaken.

    What is the resistance of your sense resistor on your board?

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Expert 1215 points

    Hi Kahler,

    I calculated the values of design capacity and energy capacity by taking into account the loss of the state of charge when we charge in 4.142V instead of 4.2V indicated by the datasheet of the element.

    It's correct for the cell terminate at 2.714V.

    I determine the chemID by use the GPCCHEM. The battery are charged by the charge system and after the relaxe, I discharge the battery at 3A.

    The sense resistor is a 2mohm.

    Sincerely,

    L.MICOU

  • 0 in reply to micou ludovic
    TI__Mastermind 25955 points
    Hi Ludovic,

    Please use the unlearned chemID with the gpcrb tool. After programming the gauge with the output from the gpcrb tool, please run a learning cycle prior to testing cold temperature performance.

    If the issue persists after repeating the steps above, please send a copy of:

    (1) Input to the gpcchem tool
    (2) Output from the gpcchem tool
    (3) Input to the gpcrb tool
    (4) Output from the gpcrb tool
    (5) Logs from the test
    (6) New gg.csv file

    Sincerely,
    Bryan Kahler