BQ4050: SOH

Hello Fabio,

   The biggest variables used in SOH is measuring coulomb counting during discharge and/or impedance of the cell. Temperature and especially low temperature is able to make the internal resistance much higher compared to if it was in ambient temperature. Although short experiences with low/high temperature shouldn't effect much of the SOH capacity prolonged exposure would. In BQStudio temperature is taken into factor in creating the ChemID to optimized for accuracy between 0°C and 50°C.
     The definition of "FullChargeCapacity/State of Health" would be the same for both gauges however the BQ40z50 uses impedance tracking to get the FFC_SOH and BQ4050 uses CEDV to get FFC_SOH. Below I attached the documentation between the difference in the algorithm to reach the target value but typically impedance tracking does a more accurate job of determining FFC_SOH of a cell.


-CEDV and Impedance tracking comparison 
https://www.ti.com/lit/an/sluaar3/sluaar3.pdf?ts=1739379051925&ref_url=https%253A%252F%252Fwww.google.com%252F

-Documentation on Impedance tracking and temperature:
https://www.ti.com/lit/ml/slyp819/slyp819.pdf?ts=1739376645801&ref_url=https%253A%252F%252Fwww.google.com%252F

-Documentation on how the ChemID/Learning cycle done is made
https://www.ti.com/lit/an/slua903/slua903.pdf?ts=1739378445118&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ40Z50

https://www.ti.com/lit/an/slva725a/slva725a.pdf?ts=1739378437783&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ40Z50