Method for determining a state noise covariance matrix for adjusting an observer of the state of charge of a battery and corresponding device

A method for determining a process noise covariance matrix for tuning an observer of a state-of-charge of a battery comprising a set of operating points, wherein the method comprises:

• a step of determining, for each operating point, a value of impedances (R0, Z1) of an electrical model of the battery;
• a step of calculating a voltage difference (r(SOCk)) between a voltage obtained by the electrical model, the impedances of which were determined upon completion of the determining step, and a voltage actually measured across the terminals of the battery;
• a step of storing the values of said impedances and of said voltage differences;
• and
• a step of producing the covariance matrix (Q) comprising standard deviations (σ[r(SOC1 . . . p)]) obtained based on the voltage differences from the calculating step for various operating points of the battery.