As the battery is further utilized in a device, its health as in its capacity and other useful parameters deteriorate till it reaches the end of life (SoH = ~70-80%).
The designer of a battery management system may use any of the following parameters (singly or in combination) to derive an arbitrary value for the SoH.
In addition, the designer of the battery management system defines an arbitrary weight for each of the parameter's contribution to the SoH value.
[2] In general, the first usage of batteries is limited to the SoH values of ~70-80% for electric vehicles and electronic equipment.
Typically this relates to instantaneous drops in the supplied voltage, and subsequent inability for the connected power electronics to operate normally.