Calculating the State of Health for a Lithium Ion Battery System

A battery's State of Health is critical to understanding how a battery degrades as it is charged and discharged over time. This degradation is caused by the increasing impedance of the cells. This video explains how this is calculated and some easier ways to understand how a Battery Management System monitors and reports this information. Topics Covered State of Health Discharge Cycles State of Health Capacity State of Health Impedance ESR Estimated Range Remaining Range Calculations Battery Capacity Fade Effect State of health, or SOH, is commonly defined as the total capacity of the battery pack today divided by the total beginning of life capacity, given in units of Amp Hours. We explain how this is calculated by the Battery Management System and why understanding state of health is important for a system. State of health explains the degradation of the battery over a number of discharge cycles. We also look at State of Health impedance as well as the more common State of Health capacity. Over time, the ESR, or impedance, of the cell will grow. This increasing impedance decreases the state of health. A battery management system looks at both of these calculations to understand how a battery pack ages. This changes how the range of a battery pack is calculate for an electric vehicle. For more information, visit https://staflsystems.com