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BQ40Z50-R1: BMS Reset Event

Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: BQSTUDIO, BQ40Z50, EV2400

Hello team,

Hope you are doing well and staying safe. When you get a chance please see below from customer:

We monitor and log the relative charge % vs time. We observed this value change drastically after what we believe to be a BMS reset event. Our android driver doesn't support reading the reset statistics, so we aren't certain yet. Our device uses SoC information to determine when to go into low power modes, so after large drops we sometimes go into a sleep mode for 6 hours. When that happens our camera goes offline, which you can see represented in this plot by the lack of data points. Do you have any recommendations or ideas of what could be going wrong?

  • Hi Randhir,

    The gauge has a lot of information. It is not possible to tell what might the cause based on their SoC plot only.  Can this customer provide voltage, current, temperature data as well?  

    Andy 

  • Andy, 

    See below customer response.

    I can provide you with as much information we have on this failure. It has only occurred in the field so our data is limited. Here are plots for the pack current, voltage and temperature (all reported by the BMS). Note that the thin straight lines are sections of missing data that occurred when our device went to sleep due to the reported SoC being below 20%. As you can see, just before our device went to sleep on 04/06 11:00 the current, voltage and temperature all look to be within normal limits.

  • Hi Randhir,

    As I mentioned before, without sufficient data, it is almost not possible to find the root cause.

    Is it possible to connect an EV2400 to the bq40z50 device and use bqStudio to capture a log file?  

    Also, how often does this "reset event" occur?  Have they checked if it is due to a hardware issue? 

    Andy