Methods and systems for predicting an unknown voltage of a battery corresponding to a future current demand for at least one time instant. The method including determining parameters of a first joint Gaussian distribution of a set of historical values of the voltage prediction of the battery from a set of historical measured physical quantities of the state of the battery stored in the memory. Determining a second joint Gaussian distribution of the unknown voltage and the set of historical values of the voltage prediction of the battery, based on a present measured physical quantities of the battery, the set of historical measured physical quantities and the determined parameters of the first joint Gaussian distribution. Determining a mean and a variance of an unknown voltage of the battery from the second joint Gaussian distribution, to obtain the predicted unknown voltage of the battery.