Operational Factors of Battery Systems

Abstract

The battery performance data given throughout this textbook are based on selected and average designs and conditions of use. These values are helpful in establishing average performance characteristics, but the actual performance of the battery may be significantly different under practical conditions. The performance of a battery under specific conditions should be obtained before any final comparisons are made or definitive designs are attempted. In addition, even for the same battery type, chemistry, or design, there are sometimes significant performance differences based on the manufacturer or between different versions of the same battery. For the same manufacturer, there are also performance variables in the production from lot to lot. The extent of variability depends on the process control specific to each manufacturer. Throughout the text in this section, conceptual battery performance and trends are presented, without reference to any particular battery, experiment, or manufacturer. These conceptual diagrams and data serve to educate about the trends, principles, and average values; they are not referenced to any previously reported specific data. 2.1 Performance Parameters The main operational parameters of batteries include cell voltage (V), capacity (Ah), energy (Wh), energy density (Wh/L), specific energy (Wh/kg), state of charge (SoC/%), depth of discharge (DoD/%), voltage limitation (charge, V), cut-of-voltage (discharge, V), effect of temperature, cycle life, calendar life, and internal resistance (Ω). The state of charge and depth of discharge are depicted in the diagram in Fig. 2.1, in the form of bars that represent levels of battery capacity. The shaded part of the bars is the remaining capacity or a gauge. On the left side of the diagram is the depth of discharge. The top of the bar would mean a fully charged battery or zero depth of discharge, while the bottom signifies fully discharged battery or 100% depth of # The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021 S. Petrovic, Battery Technology Crash Course, https://doi.