Abstract: A state of health (SOH) based control system includes: a memory configured to store an algorithm including instructions for determining a SOH of a power source; and a control module configured to receive a voltage signal indicating a voltage of the power source and execute the instructions. The instructions include: determining a state of charge (SOC) of the power source; generating a differential signal based on a change in the voltage and a change in the state of charge; determining an inflection point and an end of charge point of the differential signal; determining the SOH of the power source based on the inflection point and the end of charge point; and performing at least one of a control operation or a countermeasure based on the SOH.