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BQ78350-R1: My 12S1P 32000mAh lipo battery work with BQ78350-R1 + BQ76940 power manageboard, everything works well except the cycle count somtimes jumped to 5911 which actually is 5- 10times

user3729019
Prodigy 50 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ76940, , BQSTUDIO

LIke the title says:

My 12S1P 32000mAh lipo battery work with BQ78350-R1 + BQ76940 power ICs,  everything works well except the cycle count somtimes jumped to 5911 which actually is 5- 10times.

Now i have 40 batteries, all used below 10 times and the cycle count of 6 have jumped to 5911, and if you continue to use it, it will be still 5911 and never change again.

Battery usually works at current about 30-45A, and the charge current is 40A,.

Its works on a drone, and the designed max discharge current is 150A，actually we dont use mosfet  because we dont think its safe enough to shut the ouput off when something wrong happens.

Now just the cycle count of 5911, we cant solve it , and dont why , so pls help me.

Here is a screencut of the battery information from battery management studio:

  • 0
    TI__Guru* 81035 points

    Hi,

    Can you send your data flash settings file (.gg.csv file)? You can export this from the Data Memory screen of BQStudio.

    Additionally, if you are able to capture a log file (click Start Log on the Registers screen of BQStudio) where the jump in cycle count occurs, it would be very helpful for debug.

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 50 points

    First, thank you for your reply.

    About the log file, because battery be used on a drone, so its not easy to get one while cycle count jump occurs, even if it did not happen everytime, but I will try and send here if got one.

    Now we are testing batteries after we opened the protocol checkout(  PEC )， don't know if it is because of this set item, it is not set before.

    Here is the setting file(.srec, BQStudio can read):

    32000-12s.zip

  • 0 in reply to user3729019
    TI__Guru* 81035 points

    Thanks for sending the srec. We have our annual BMS Deep Dive conference this week, but I should be able to take a quick look at it on Monday when I have access to an EVM. However, I do not know of anything in the settings that could explain this large jump in cycle count since it should only be able to increment by one.

    If you suspect anything in the SMBus communication, this may be able to explain how the value could change. The cycle count value can be written in data flash accidentally for example.

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 50 points

    Hi Matt

    Thank you so much for your respond.

    So appreciate for you check of setting next Monday.

    If we set the checkout on, theoretically it should not any jump even if there is disturbance exist， right?

    We have test 10 times more,  didnot see any jump of 5911 yet, but got small jump, like from 3 to 1. It is so wired!

    We will keep testing all batteries ,and keep touch with you.

  • 0 in reply to user3729019
    TI__Guru* 81035 points

    Cycle count should never be able to go down, so something must be writing to the data flash. I wonder if there is noise on the SMBus transactions that is causing a wrong command. Are there writes to data flash during operation?

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 50 points

    Have tested a lot till now, no 5911 cycle count anymore after we set on the checkout, we will continue to test.

    For the cycle count down prolem, we dont write anything to flash while working, just send read command.

  • 0 in reply to user3729019
    TI__Guru* 81035 points

    I'm glad to hear that it is no longer showing the jump to 5911. Hopefully enabling PEC has helped to prevent this. Let me know if you see the issue again.

    Thanks,

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 50 points

    I think prolem have been solved, no 5911 cycle counts anymore. Thank you so much!