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BQ40Z50-R2: Battery charging problem

Renaud BLAIZOT
Prodigy 50 points
Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQSTUDIO

Hello,

I am facing a problem : I can't charge a 3-Series Li-on battery with bq40z50-r2. For information, I'm using a LTC1960 as battery charger.

I've followed procedures and tried to manually activate/desactivate the FETs for charge/discharge tests and this is what I'm obtaning : 

OperationStatus[XCHG] pass to 0, OperationStatus[CHG] pass to 1, ManufacturingStatus[CHG_TEST] pass to 1, but it seems that the GaugingStatus[DSG] doesn't pass to 0 to indicate a charging status...

Do you have any idea why I can't charge my battery? For information, there is no problem with discharge (manually or automatically by putting FET_EN to 1).

Thanks in adavance for any help.

Best regards,

Renaud

  • 0
    TI__Expert 6575 points
    Hi Renaud,
    The GaugeStatus[DSG] bit only clears when the gauge detects that it is in charge mode.
    The gauge goes to charge mode when the Current() > Charge current threshold.
    Since the charge FET is on, there should be no problem to charge the pack.
    I would recommend using the FET enable instead of the FET test to do this test so that the gauge firmware can automatically control the FETs.
    If you are still having trouble charging, could you please post a log file when you are trying to charge (The "start log" button in the Register tab) .
    Regards,
    Swami
  • 0 in reply to Swaminathan Ramanathan75031
    Prodigy 50 points

    Hi Swami,

    Thanks for your reply.

    There is indeed no current coming from the charger, but I don't understand why... I send you a log file where the gauge is connected to the charger with FET_EN on so that the firmware can control the FETs. I've switched off the alim during the test so it could pass in discharge mode.

    I also send you my srec file if there is something I've maybe missed in the configuration which could explain why my gauge and my charger don't communicate.

     Best regards,

    Renaud

    bq40z50r2.zip

  • 0 in reply to Renaud BLAIZOT
    TI__Expert 6575 points
    Hi Renaud,
    Looks like the LTC1960 does not take direct SMBus commands from the gauge, it only has an SPI port.
    The [BCAST] bit is enabled in your settings and it looks like the Charging Voltage and Charging current are being reported correctly.
    The gauge will broadcast this to (8-bit address) 0x12 as per the SBS specifications.
    I would check with a I2C bus monitor to check that the gauge is broadcasting the data.
    I would also check if the pack will charge with a power supply.
    Regards,
    Swami
  • 0 in reply to Swaminathan Ramanathan75031
    Prodigy 50 points

    Hi Swami,

    Thanks for your reply.

    I've finally managed to charge my cells with the LTC1960 with SMBus, a thermistor was missing on the charger to start the charge.

    I've made my learning cycle and export a golden file, but I encountered another problem with a new gauge. When I tried to import my .srec file on a new board, the operation didn't success (it stopped in the middle of the loading of the file), and after that, impossible to auto-detect the gauge with bqstudio...

    Is there something wrong with I've done? And is there a way to restaurate the gauge?

    Thanks in advance for your reply.

    Best regards,

    Renaud 

  • 0 in reply to Renaud BLAIZOT
    TI__Expert 6575 points
    Hi Renaud,
    If the srec programming stopped in the middle, most likely the gauge will still be in boot rom mode.
    You can manually select the gauge in bqStudio and try flashing the srec again.
    However if that fails, there is a remote possibility that the device is not recoverable.
    Regards,
    Swami