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Problems with bqStudio => EV2300 => bq34z100-g1 on custom hardware

David Pfaltzgraff
Expert 2465 points
Other Parts Discussed in Thread: BQ34Z100-G1, BQSTUDIO

I am trying to follow the procedure as described in SLVA725 to submit chemID data. I have bqStudio running on Windows 7 connected to an EV2300 which connects through the I2C bus to a bq34z100-G1 on my hardware. I am trying to set this system up for 4 NiMH cells in series - specifically Energizer NH15VP, 2300mAh.

When I run bqStudio, I am able to calibrate the current and voltage as expected. However, the internal temperature is always reported as -39.2C and I am unable to change this. First question: What am I missing?

As I collected data as per SLVA725, I noted occasional occurrences of the error "772,No acknowledge from device." Since this is intermittent, my presumption is that it may be a timing error. Next question: Is there a way to control the I2C clock rate from within bqStudio?

When these occurred, bogus data was saved in the data file. Since the expected data is fairly smooth, it was easy to edit the file and put reasonable data in the voltage, current, and temperature columns. When plotted, it looked reasonable. However, the chemID tool didn't like it. One of the reported issues was that the temperature was "out of range."

The capacity of the cells is 2300mAh. They were discharged as 152mA for 14 hours which at 2125 is close to the expected value. chemID suggests decreasing it even lower. The C/10 rate would have been 230 mA.The end result is that chemID suggested using 6102 which is rated at 500 mAh. I had started out with 6100, which is rated at 3700 mAh.

How can I proceed?

  • 0
    TI__Guru 73830 points

    David,

    You should be able to calibrate the internal temperature using the Calibration screen in bqStudio. Are you sure that the internal temperature is selected to be reported as Temperature()? This is selected by setting the TEMPS bit low in the Pack Configuration register.

    The capacity rating listed with the ChemID was the capacity of the cell used to create the ChemID. The capacity is not stored in the ChemID, so it does not matter. The important requirement is to get a good OCV match for to the cells.

    You should normally discharge the cells down to the Cell Term Voltage. If the Cell Term V is set much higher than the true low end voltage of the cell, then you ay have to discharge it lower to allow the program to find a good ChemID match.

    Tom

  • 0 in reply to ThomasCosby
    Expert 2465 points

    Hi Tom,

    I presumed this would be set by selecting the "Internal Temp" button on the calibration screen. But, checking it in the "Data Memory" window, I see that it is set - RED. The calibration screen shows "Gauge" -32.9. I enter 22.0 in the "Applied Temperature" window, select "Calibrate Temperature", and click on the "Calibrate Gas Gauge" button. The progress bar pops up and goes away in a few seconds and the green checkmark shows up. At this point, turning on the "AutoRefresh" just leaves both the Gauge temperature and the info next to the IC icon showing -32.9. I would have expected these to be updated on the next refresh. Obviously something is not happening.

    I think the chemID is a reasonable match as the nominal voltage levels agree for both batteries. The difference is in the capacity.

    By "Cell Term Voltage", I presume that this is the parameter in the IT Cfg table of the "Gas Gauging" memory. Is this a voltage per cell, or for the pack. My system is set at 3000 mV. Where did this come from? (A default or from the chemID? It would be logical for this value to be calculated from the chemistry times the number of cells.)

    Is there a way to reset the bq34z100-g1 back to the factory defaults? I'm not sure I want to, but I need to be able to recreate the process whereby I got there.

    Thanks, Dave

  • 0 in reply to David Pfaltzgraff
    TI__Guru 73830 points

    Dave,

    Calibrating the Internal Temp sensor does not select it to report as Temperature. You have to set the TEMPS bit low to select it.


    The Cell Term Voltage is at the cell level and 3000 is the default setting for a Li-Ion cell. You will need to adjust it for a NiMH cell.

    You can reset the device back to the factory default values by programming the default srec and it can be downloaded from the product website.

    Tom

  • 0 in reply to ThomasCosby
    Expert 2465 points

    Can you provide a link for the srec?

    I wasn't able to find anything where I expected it at www.ti.com/product/BQ34Z100-G1

    Thanks

  • 0 in reply to David Pfaltzgraff
    TI__Guru 73830 points
    Dave,
    The firmware link is under Software.
    Tom

    www.ti.com/.../toolssoftware
  • 0 in reply to ThomasCosby
    Expert 2465 points

    Duh... I looked right over it.

    Thanks.