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bq78Pl114s12 - RSOC reading

Other Parts Discussed in Thread: BQWIZARD, BQ78PL114

Hi,

We have a problem with the RSOC readings, the RSOC value jumps (either up or down) 12 - 15% of the value initially displayed when the battery pack starts charging or discharging.

An example, say the battery charged to 100%, when a load is connected to it, in the first few minutes, the RSOC is shown as 100%, and then thereafter drops to roughly 80%, and thereafter the RSOC value displayed drops linearly till the desired discharge voltage value.

The data collection procedure stated in SLUA505B application report was followed and the AuxChemFileUtility in bqwizard software was used with the correct parameters to generate the auxiliary file.

Any suggestions on what could be causing this problem?

regards,

suja

 

 

  • Hello Suja,

    you need to consider, that FCC is not a fixed value anymore. The bq78pl114 re-calculates FCC quite often.

    FCC is a function of temperature, age and load. The more current you draw, the less energy you get out of the battery, the smaller FCC will be. So if you start to discharge the battery, the load situation changes and after a recalculation the bq78pl114 adjusts the FCC value to the current load situation. This is very smart, but because the jump in RSOC is noticeable by the unaware battery user, it comes across as a fault.

    Use the log feature of the bqWizard and have a look at FCC, RSOC and current. You will notice the dependencies.

    Regards, Heye