• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 64 subscribers
  • Views 257 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ78350-R1: Bq78350-r1 recorded wrong lifetime data value.

mehmet özel
Prodigy 120 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ76940, BQ78350

Tool/software:

Hello Ti Team,

I have a question about the lifetime data of Bq78350-r1 indicator.
Our bms structure includes Bq76940 and Bq78350-r1 and is 10S,2P.
we noticed that some battery life data is wrong. Life time data recorded that cell 10 min voltage value is 860mV and maximum temperature of the cell is 127 degree but we know that these values ​​are wrong because we check cell 10 voltage during this period and cell temperature is 25C since battery is in 25C chamber. Also, battery waited in shutdown mode for this period. no charging, no discharging.
Anyway this problem has been observed in several batteries.
I am sharing the log data.

Do you have any idea about the reason for this? and have you encountered such problem before?

cell10_lifetime.gg.csv

  • 0
    TI__Guru 61006 points

    This looks like a temporary electrical problem with the voltage on the temperature sense and cell voltage sense lines. How do you check that cell 10 voltage during this period (how long is this period?) is not 860mV *at the pin* of the AFE?

  • 0 in reply to Dominik Hartl11
    Prodigy 120 points

    Hello Dominik,

    We checked using the data logger on the cell soldering point. You may think that there is an electrical problem because of the 860mV problem, but 127C cell temperature does not make sense. If NTC is open, BMS measures -56C not 127C.

    We also did a vibration test to understand that this problem is due to soldering crash, but we did not observe any problem.
    we cannot reproduce the fault. It would be easy to reproduce if it was an electrical problem.
    This failure rate is 4 out of 150 products. (4/150)

    I am uploading the bq78350_R1_v1_04_build_26.srec firmware inside the bq78350-r1.
    Could it be that there is any conflict with the bq76940 AFE?

  • 0 in reply to mehmet özel
    TI__Guru 61006 points

    How many units are showing this problem? There's always the chance that something is damaged inside the AFE. Is this something that you can reproduce on several AFEs? The FW reads the data from the AFE, basically the output from an ADC and then converts this either to mV or deg.C. Both the voltage and the temperature indicate that the conversion result was small and while you are correct that an open thermistor produces a low temperature, if something in the system causes the voltage on that pin (or inside the AFE where the pin is connected internally to a pad on the silicon) to be too low, then the temperature is going to be excessively high.

    Therefore I doubt that this is a FW problem and more likely a problem with your AFE (e.g. ESD damage that causes unreliable operation).