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Original question:

BQ34Z100-G1: State of Charge, Remaining Capacity and Full Charge Capacity registers are always 0

BQ34Z100-G1: 36V LiFePo4 battery capacity remains 0

Paul Bareil
Prodigy 130 points
Part Number: BQ34Z100-G1

Hello all,

I have a 36V(12 cell with 42+V fully charged) LiFePo4 63Ah battery. I tried setting everything and the capacity stays to 0. I have tried different Chemistry too.

Also, the Ra table changes but I get a "target bqz container is old and needs to be updated".

I attached the current .gg.csv file.

Any idea what is the problem?36V-63Ah_battery.gg.csv

  • 0
    TI__Guru** 105760 points

    Hello Paul,

    Did you set the VOLTSEL bit and set the voltage divider so the max voltage at BAT pin is 1V? You will also need to upload the divider ratio. After this you'll have to do a voltage calibration. Are you using an EVM or custom board?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 130 points

    Thanks @Wyatt!

    I have set the VOLTSEL bit so that the external resistor are used. I have the EVM so I set the jumpers for 48v. Since my battery goes to 43v max the BAT I put never reaches the max value. Could it be the problem?

    I recalibrated the module so that it reports the same thing I read with multimeter. It reads the right voltage now.

    But the battery meter is 0

  • 0 in reply to Paul Bareil
    TI__Guru** 105760 points

    Hello Paul,

    So the battery gauge and DMM report the same value now, what is your battery meter? It sounds like the issue was fixed if the multimeter and gauge report the same thing.

    You will need to find the correct chem ID and to perform a learning cycle now that the gauge is reading voltage correctly.

    Sincerely,

    Wyatt Keller  

  • 0 in reply to Wyatt Keller
    Prodigy 130 points

    Hi Wyatt,

    I have uploaded the right chemistry. However, I have set the "Design Capacity to 32767 mAh and in the "Remaining Capacity", I get a 885mAh reading and full charge Capacity 945mAh. This is when the battery voltage is 41V. As soon as it drops to 39V it says there is 0mAh remaining capacity. However, at 39V there should be much more than that remaining.

    The way the chip calculates the actual remaining capacity is not clear to me. What are the actual parameters that the device uses to make its calculation? What are the most importnat ones?

    Thnaks.

  • 0 in reply to Paul Bareil
    Prodigy 130 points

    I have some news. I enabled the IT impedance track. (IT_ENABLE) and boom it started displaying 100% like it should.

    What happened?

  • 0 in reply to Paul Bareil
    TI__Guru** 105760 points

    Hello Paul,

    You have to send IT_ENABLE for the algorithm to start actively running for RemCap, FCC, and SOC calculations. The values may not be accurate if IT_ENABLE isn't set to 1.

    Sincerely,

    Wyatt Keller