Method for estimating the state of health of an electric or hybrid vehicle battery

A method for estimating the state of health of a battery of an electric or hybrid vehicle, comprising:

• (a) a step of charging the battery until the battery reaches a maximum state of charge SOCmax;
• (b) a first relaxation step, during which the battery is not used for a first duration;
• (c) a step of discharging the battery until the battery reaches a state of charge that is less than or equal to a non-zero target state of charge SOCtarget, with the discharging step being carried out in a number k of running cycles of the vehicle, with k being a non-zero integer, and, for each running cycle n where 1≤n≤k, the capacity Qn discharged by the battery is determined;
• (d) a second relaxation step, at the end of the running cycle k, during which step the battery is not used for a second duration;
• (e) a step of determining a state of charge SOCOCV of the battery as a function of the open-circuit voltage, with the battery not being used;
• (f) a step of determining an initial discharge capacity Qi of the battery in a new state based on the state of charge determined in step (e) and on a previously established correlation for the battery in a new state and correlating the initial discharge capacity with the state of charge of the battery;
• and
• (g) a step of estimating the state of health SOH of the battery based on the total capacity discharged by the battery during the discharging step (c) and on the initial discharge capacity determined in step (f).