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BQ78350-R1: overload current threshold

Matteo Crida
Prodigy 60 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ76940, , BQSTUDIO, BQ78350

HI

we've realized a bms with bq76940 an the companion bq78350-r1.

We are trying to record the log files, using bqstudio and EV2300, to send to TI site for the CEDV calculation.

We are making the tests as instruction and we need to sink 3A and 6A from the battery pack, but, over 2A the bms go in protection mode, setting AOLD and AOLDL.

I've not understood what parameters i've to change to increase the threshold of overload.

Thanks in advance

Best regards

Matteo Crida

  • 0
    TI__Intellectual 1840 points
    Hi,

    You may want to ask this question in the Battery Management - Monitors, Protectors, Authentication and ID Forum.

    But taking a quick look at the datasheet, it seems like you can adjust the threshold by configuring OCD_T3:0 (Bits 3–0) of the PROTECT2 (0x07) byte.
    See page 39 of the bq76940's datasheet.

    Hope this helps,
  • 0 in reply to Nabil M
    Prodigy 60 points
    Hi
    i've tried to post in Battery Management - Monitors, Protectors, Authentication and ID Forum, but when i insert the part number bq78350 automatically change in GAS gauge forum.
    I can't change only the bytes you said because using bq studio they aren't available.
    I've already tried to increase OCD current treshold to -10000 mA but the behaviour is the same.

    I've also tried to calibrate cc offset and cc gain with bq studio, but at both commands it returns an error "Raw calibration block size returned after command 0xf081 and 0xf082 is an incorrect lenght" ad i don't kow how to calibrate in other ways.

    Could anyone help me?
    Thanks in advance
  • 0 in reply to Matteo Crida
    TI__Intellectual 1840 points
    Hi,

    This is concerning the bq76940 or the bq78350 ? I'm talking about changing the bytes in the bq76940, not in the bq78350, which is a fuel gauge.
  • 0 in reply to Nabil M
    Prodigy 60 points
    Hi
    I'm interfacing bqstudio to bq78330 throught ev2300 connected with smbus.
    I'm connecting only with the companion (bq78350) and it dialogues with bq76940 by i2c programming parameters.
    But i don't see the fisical register OCD but only the OCD current (in mA), i think the companion calculates the parameter to program in OCD register to match the right desired current.
    Also I can't do the current calibration because it returns the error explained above. How can I fix it?
    Thanks
    Matteo Crida
  • 0 in reply to Matteo Crida
    TI__Intellectual 1840 points

    Hi Matteo, 

    Take a look at this forum: https://e2e.ti.com/support/power_management/battery_management/f/180/p/484700/1747783

    They seemed to be having a similar issue a while ago. Could be the firmware. Check out Tom's reply with the proper bqz file. 

  • 0 in reply to Nabil M
    Prodigy 60 points
    Hi
    thanks for your help
    I've updated the bqz file (pheraps is more useful if TI update the bqstudio installer) and i've made the correct calibration and the current measurement now is very accuracy
    But the main problem is the same: when i attach a load for more than 2000mA the bms go in protection mode, setting AOLD and AOLDL.
    With bqstudio i've setted the OCD threshold at -10000 mA, i think that bq78350 (i can only interface with it) calculate the correct OCD byte to program in bq76940 that you said previously.
    I don't know what other parameters i've to change to attach the load i need.
    Thanks for you help