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BQ34Z100EVM: Update Status won't update to 0x05 after charge

Alexander Young67
Prodigy 90 points
Part Number: BQ34Z100EVM
Other Parts Discussed in Thread: GPCCHEM

I'm trying to run the learning cycle using the BQ34100EVM module along with a single Samsung 35E cell.

I have attempted to run it twice now but after the charge section, I never see the update status go to 0x05 after the VOK bit clears in the rest section directly after the charge.

I have attached the registers export(after I rebooted everything from the "failed" test) and the log of the test.

I'm using a power supply as a charger right now since the products real charger is still under development/ test.

Thanks in advance.

8688.ti.zip

  • 0
    TI__Mastermind 25955 points
    Hi Alexander,

    A few things:

    1) What chemID is loaded on the device? Please use the GPCCHEM tool to ensure a good match. The gpcchem tool may be found here: http://www.ti.com/tool/gpcchem

    2) The log file cuts off the charge/relax portion. The maximum voltage seen in the log is 4117 mV. Please ensure the cell is fully charged and rested prior to the discharge portion. Please also ensure that the cell is fully discharged to terminate so a 90% drop is seen. RC went heavily negative (-2291 mAh) with an initial Qmax Cell 0 of 1000 mAh. Please update Qmax Cell 0 to be the capacity of the cell for the initial value.

    Please make sure to follow the steps in Section 8 of the Datasheet when configuring this gauge (Qmax cell 0 adjustment is at step 5, section 8.2.2.1.5).

    3) The current on discharge varies between -672 mA and -507 mA. Assuming a capacity of 3500 mA, the discharge rate here is variable between C/5 and C/7. The -672 mA rate is very close to crossing the C/5 threshold to C/4, please consider giving a bit more margin... try at a C/5.5 discharge rate.

    Sincerely,
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Prodigy 90 points

    Bryan, thanks for following up so quickly.

    1) I have chemID 0x2361 programmed into the chip.

    2) I cut off the charger once it hit ~68mA, regardless of the cell voltage. I unfortunately stopped the test/ log once the update status never changed to 0x05 after the VOK bit cleared; I did this since the document stated to start over if the update status doesn't change. Should I stop the charger once it hits the terminating charge voltage AND current? I just updated Qmax Cell 0 to the capacity of the cell, I overlooked having to update that - thanks for catching that.

    3) I will give that a shot with some type of electronic load, I just used a resistor to discharge in this particular test.

    Thanks,

    Alex

  • 0 in reply to Alexander Young67
    TI__Mastermind 25955 points
    Hi Alex,

    Sounds good!

    If the issue persists after using the electronic load for a constant current discharge, please investigate the chemID. The gpcchem tool should be used to determine a match.

    Sincerely
    Bryan Kahler
  • 0 in reply to Bryan Kahler
    Prodigy 90 points

    Bryan-

    I was finally able to run a test with a constant current load after tweaking the settings you mentioned and saw the update status go to 0x05 but now it's stuck there after the full completion of the learning cycle. I also noticed two other things; the FC bit never got set, although after reading through the datasheet it seemed like I met all the criteria for that bit to be set?

    With all that said, the test setup is still together, and if there is something I can do without having to completely start over to get it to roll over to 0x06, let me know.

    I attached the logs of the test, I was trying to avoid running the chem tool since the exact cell I'm using is a ChemID already but if you think that is the best path forward I will proceed. Is there any chance the data I have attached here could be used for that tool? Although I know the discharge rate is nearly double the specification in the directions.

    Thanks again for your help!

    -Alex

    ti2.zip

  • 0 in reply to Alexander Young67
    TI__Mastermind 25955 points

    Hi Alex,

    Please ensure FC sets by setting FC Set % = -1 and ensuring the taper current requirement matches that of your cell.

    To advance from an update status of 0x05 to 0x06, please ensure your discharge is larger than C/10.  Please try decreasing the discharge rate as it appears to be over 1C with respect to the values in the gg.csv file.  

    With such a large discharge, the voltage rebounds after discharge and DOD drop can be less than 90% as a result.  Please try a discharge between C/5 and C/10 for this learning cycle.  

    After the pack is learned, the DOD drop % requirement is decreased from 90% to 37% for subsequent updates.

    Sincerely,

    Bryan Kahler