Method and apparatus for estimating a state of charge of a battery

A battery management system for estimating a state of charge of a battery, the battery management system comprising:

• a battery model specific to the battery, the battery model providing a section-wise defined correlation of terminal voltage values depending on state of charge values, wherein a curve of the section-wise defined correlation is strictly monotonic decreasing in a number of sections and strictly monotonic increasing in another section, and wherein each of sections of the battery model delimits a monotonic dependence of the correlation from others of the sections;
• a measuring module configured to measure a terminal voltage value of the battery;
• an indexing module operable to identify one of the sections of the battery model based on an operational condition of the battery;
• a correlation module operable to retrieve, within the identified one section of the battery model, a state of charge value correlating to the terminal voltage;
• and
• an output module for returning the retrieved state of charge value as an estimated state of charge of the battery, such that the retrieved state of charge value is displayed as the estimated state of charge of the battery and stoppage or an interruption of operation of equipment powered by the battery is avoidable.