Akku4Future — Methods for data generation to compute state indication

Abstract

To estimate state-of-charge (SOC) and state-of-health (SOH) of a lithium ion battery as exact as possible, the terminal voltage, the terminal current and the cell temperature have to be measured. The easiest model of a battery is an ohmic-capacitive (R-C) series-parallel circuit. Two measurement methods are shown how to get ready to estimate SOC and SOH in a simple but precise manner. The first measurement is a defined capacity package being discharged a battery until the battery is empty. The packages give data points in the correlation curve for open-circuit-voltage (OCV) and SOC. This is base for SOC estimation. To take degradation into account hundred full cycles are examined on the test cells with 15 parameter variations on the above mentioned three parameters voltage, current and temperature.