NOVELTY - The method involves acquiring a value of a physical quantity representative of aging of a lithium-ion battery (100). Age of the battery is acquired (105) using sum of durations of cycling phases and durations of storage phases and mapped (110) with a reference value of physical quantity. A ratio between a measured value and the reference value is calculated (115), where the calculated ratio value lies between 0.1 and 1.9. A state of ageing of the battery is stored (140) in a memory.    USE - Method for calculating a ratio between a measured value and a reference value of a physical quantity representative of aging of a lithium-ion battery of an electric or hybrid vehicle e.g. electric or hybrid car (all claimed), for homogenizing ageing of the battery.    ADVANTAGE - The method enables calculating a ratio between the measured value and the reference value of the physical quantity representative of aging of the lithium-ion battery so as to realize homogenize conduction of a driver function with a conduction of the reference value for homogenizing a state of wear of the battery of the vehicle according to a state of wear of reference, thus assuring homogenization of lifetime of the battery.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a method for determining a criterion of severity of control of a driver of an electric or hybrid vehicle impacting on ageing of a lithium-ion battery of the vehicle relative to a reference    (2) a method for homogenizing ageing of a battery of a electric or hybrid vehicle.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart illustrating a method for homogenizing ageing of a battery of an electric or hybrid vehicle.'(Drawing includes non-English language text)'    Step for acquiring value of physical quantity representative of aging of lithium-ion battery (100)    Step for acquiring age of battery (105)    Step for mapping age of battery with reference value of physical quantity (110)    Step for calculating ratio between measured value and reference value (115)    Step for storing state of ageing of battery in memory (140)