A battery charger includes an input supply terminal configured to receive a supply signal and a battery terminal configured to be connected to a battery. A supply switching circuit is arranged between the battery terminal and the input supply terminal. A control device generates a control signal to control operation of the supply switching circuit. A fuel gauge device provide a digital estimation of a voltage signal across the battery. A correction device modifies the control signal in response to the digital estimation of the voltage signal across the battery if that digital estimation is outside of a value range between two thresholds.