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BQ20Z75 v 1.60 PF status AFE_C, SOTD

Kjell Ramberg
Expert 1375 points

Dear all,

During the last year we have experienced a lot of technical problems with batteries failing. The most ferquent failure is for some of the batteries the PF status bit AFE_C being set, - and for others the PF SOTD bit being set. When the SOTD bit is set the temperature reading is always around 126 deg C.

We have a temperatur strip Attached to the battery indicating temperature between +40 - +72 deg C and we are 100% sure that the batteries have never been exposed to temperatur above +40 deg C. We have checked that for the batteries with SOTD bit set the NTC is Connected as it should and there is no hardware failures.

I have two questions:

  1. If the reason for the SOTD-bit being set is electrical noise etc due to the type of loading of the battery, - is it likely that the temperature indicated in the bq gas gauge software  should always be set to the same temperature - around 126 deg C?
  2. To be more robust for electrical noise disturbing the internal communication with the AFE, we have increased the AFE Fail limit from 10 to 20. We plan to increase it further til 40. If this does not help, - what is TI's comments setting this function to 0 (disabling the function)? Would that endanger most of the 2.level safety functions?

Any comments will be very much appreciated because we need to find a solution for the batteries that are failing

Best regards

Kjell 

  • 0
    Expert 1375 points

    Anybody at TI that might assist (please).......

    I fully understand that my questions probably are difficult to give a precise answer to but if you could comment on the following I would be more than happy since we have run into a lot of trouble lately with a lot of battey failures.

    The most frequent PF failure is SOTD or SOTC flag has being set. The temperaure reported is always around 126 deg C. If the PF failure is caused by electrical noise is there a reason for the temperature reported is always the same ?

    Best regards

    Kjell