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Original question:

BQ76940: ambient temperature setting for of CEDV gas gauge calibration

BQ76940: BQ7694003

prasanna dhayalan
Prodigy 30 points
Part Number: BQ76940

Hi, 

I am facing few issues in dealing with the, High temperature GPC test. As per the manual I need to perform low current and and high current discharge at 45 deg C  on my Battery pack.  But the Over temperature 60degC protection set in the GG ASIC is triggered before I can complete my data logging.  So this affects my data matrix in the high current and high temperature region. I would like to know if there are any other ways to solve this. I see below two options for solving this:

1) performing the high temperature discharge test at lower temperature than the proposed value: 35 deg C so I don't trigger OTD cutoff. 

2) I can reduce the high current setting to much lower value so that it takes longer for the Battery cells to heat up and I could finish the test. 

Can you please inform me on the effects of above mentioned solutions in regards to the accuracy of SOC calculation by my BMS.

Thanks!

  • 0
    TI__Guru* 81035 points

    Hi Prasanna,

    Both of these options are valid to prevent triggering the over-temperature during discharge fault. However, you should keep in mind that this fault will trigger in your application if your cells are going to get this hot under your application conditions.

    If you believe your cells will not get this hot during normal application conditions, then you can increase the OTD threshold while you collect the data for the GPC. It is a good idea to adjust fault thresholds as needed in order to collect the full range of data.

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 30 points

    Hi Matt, 

    Thanks for the fast response. AS for increasing OTD limit, is it fine to accept the increasing the OTD limit during SOC calibration test, wont this hav impact on the battery cell performance as this might be above recommended usage limits 60 ded C during discharge.

  • 0 in reply to prasanna dhayalan
    TI__Guru* 81035 points

    Hi Prasanna,

    I agree you do not want to exceed the usage limits of the battery cells. In this case, I recommend the first option you mentioned:

    1) performing the high temperature discharge test at lower temperature than the proposed value: 35 deg C so I don't trigger OTD cutoff. 

    Best regards,

    Matt