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BQ34Z100: Full Charge Capacity not getting set correctly

Evan Beeton
Prodigy 120 points
Part Number: BQ34Z100
Other Parts Discussed in Thread: BQSTUDIO, , GPCCHEM

After configuring the bq34z100 all appears correct, except for full charge capacity and remaining capacity.  It appears to measure voltage and current correctly.  Is there a correct order for configuring the parameters?  Or is one setting so mis-configured that the bq34z100 has no idea as to what to do?  I've attached the .gg and .srec files.34z100.zip

  • 0
    TI__Mastermind 25955 points
    Hi Evan,

    The gauge has not been through a learning cycle. Update status is at 00. This means that Qmax has not been updated, nor the Ra tables. Enable IT and run a learning cycle to update these values.

    When you enable IT, Update status will go to 0x04. After qmax updates, update status will be 0x05. After the ra tables update, update status will be 0x06.

    Here is a generalized app note for achieving a successful learning cycle ( www.ti.com/.../slua903.pdf ). Please note that there are a few differences such as update status will not go to 0x0E with this device because this device does not incorporate a protector.

    As an aside, is there a reason you are using the bq34z100 instead of the bq34z100-g1? The bq34z100 is not recommended for new designs (NRND) and can be easily updated with the bq34z100-g1 firmware which will also allow you to use the newer bqStudio, instead of EVSW. For new product development, bq34z100-g1 contains the most recent firmware and toolchain.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Prodigy 120 points

    This is an existing design.  The GasGauge is separate from the battery pack.  The GasGauge is used to get a rough idea as to state of the battery pack.  We are moving to a battery pack with a larger capacity.

    I am trying to go through a learning cycle.  However the Update Status doesn't ever seem to change from 4 to 5/6.  Looking through the documentation, I'm guessing I'm not meeting the 4 uV/dt requirement for some reason.

  • 0 in reply to Evan Beeton
    TI__Mastermind 25955 points
    Hi Evan,

    If you can take a log and 1sec and analyze it, you should be able to determine if you are meeting this condition.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Prodigy 120 points

    I can watch the first discharge cycle and see that the passed_charge almost reaches the design capacity of the battery.  I let every thing sit overnight.  Then I watch the first charge cycle and see that the passed_charge goes back down until it reaches zero.  Assuming that I should wait until the GasGauge say full_charge rather than the charger, let it stay in this "state" for many hours.  The flags value never says full_charge and the update_status never changes to 5.

    1. Should I reset the GasGuage in between the first discharge and the first charge cycles?

    2. Am I correct in assuming that the FC bit should be set?  If so, what could be preventing the GasGauge detecting FC?  The GasGauge does go into SLEEP mode if I wait a couple of minutes after the voltage() reaches the charging_voltage and current() goes to zero.

  • 0 in reply to Evan Beeton
    Prodigy 120 points
    I changed FC Set and TCA set to -1 hoping that would make difference, it didn't.
  • 0 in reply to Evan Beeton
    TI__Mastermind 25955 points
    Hi Evan,

    FC Set % should = -1.

    Please do not reset the gauge between cycles.

    Please ensure your current taper settings are proper for the battery. A good guide to follow is found here: www.ti.com/.../slua903.pdf

    Make sure you allow the battery to rest fully after charge and discharge, as described in the guide linked above.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Prodigy 120 points

    I still can't figure out why the update_status is not being updated.  I have attached dump of some interesting variables after the second discharge cycle.  As you can see the update_status is still 4, not 5 or 6.  You can see that the passed_charger is what one expect for this battery capacity.  When the battery reaches the fully charged state (FC=1) the passed_charge will be about zero.  I don't know if this is expected.  Also, the available capacities will also be near zero when the battery reaches the fully charged state.  What am I missing?

    Status 0x600b
    Flags 0x106
    Pack configuration 0x950
    Voltage 12724 mV
    Average current 2609 mA
    Current 2611 mA
    State of charge 0 %
    State of health 0 %
    Passed Charge 5801 mAh
    Depth of discharge 0x3e58 num
    Charge voltage 14600 mV
    Charge current 3000 mA
    Internal temperature 251 0.1 degree C
    Remaining capacity 0 mAh
    Full charge capacity 0 mAh
    Nominal available capacity 5857 mAh
    Full available capacity 5857 mAh
    Design capacity 6000 mAh
    DF config version 6
    GasGuage build date 60 29-Feb-1980
    Device type 0x100
    Hardware version 0x80
    Firmware version 0x6
    Chem ID 0x439
    Time to full 176 minutes 2:56
    Discharge cycle count 1
    Running in Full Access mode
    Update status 0x4
    Voltage divider 19290
    Max Temp 355 0.1 degree C
    Min Temp 209 0.1 degree C
    Max Charge 3045 mA
    Max Discharge 65052 mA
    Max Pack Voltage 14668 mV
    Min Pack Voltage 10772 mV
    Lifetime Flash Count 81

    Thanks,

    -Russ

  • 0 in reply to Evan Beeton
    TI__Mastermind 25955 points
    Hi Russ,

    Is this an older design or is there a compelling reason to be using the older bq34z100 instead of the bq34z100-g1?

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Prodigy 120 points

    You are correct, this is an existing design.  All that is being done is to increase the battery size from 3400mAh to 6000mAh.

  • 0 in reply to Evan Beeton
    TI__Mastermind 25955 points
    Hi Evan,

    Please use the GPCCHEM tool to determine the chemID that has the best match for the new cell.

    http://ti.com/tool/gpcchem

    With the new chemID programmed, please run a learning cycle.

    Sincerely,
    Bryan Kahler