SoC and SoH are two important metrics for assessing battery performance, but they measure different aspects. Below is the content of SoC vs SoH.
- The state of charge specifically refers to the present percentage of a battery’s total energy capacity that is available for use. It is an instant, real-time metric representing at any given moment what portion of full charge capacity the battery holds. Methods for determining SoC include tracking discharged/charged energy flows in and out of the battery and measuring open-circuit voltage.
- On the other hand, state of health（SOH) represents the general condition and gradual lifespan degradation of a battery in terms of its ability to store charge compared to when it was new. It indicates the long-term durability and life expectancy of the battery. SoH is calculated by taking the total current maximum capacity and dividing it by the rated capacity when the battery is brand new.
So while SoC can remain high if a battery was recently charged, the SoH could be declining if the battery is showing signs of internal wear and capacity loss over numerous charge/discharge cycles through its lifetime. Therefore, both instant SoC estimates and long-view SoH evaluations are important for properly managing and optimizing the use of batteries.