NOVELTY - The method comprises (a) acquiring a state of charge relating to a level of charge of an accumulator battery (5), (b) measuring values of the temperature of the accumulator battery at a first state of charge and at a second state of charge that is different from the first state, (c) estimating the value of the temperature of the battery at a future third state of charge, as a function of the values of the temperature measured in step (b), and (d) controlling temperature of the accumulator battery as a function of the value of the temperature estimated in step (c).    USE - The method is useful for regulating temperature of an accumulator battery that is useful in a car (all claimed).    ADVANTAGE - The method is capable of easily regulating temperature of the accumulator battery thus improving the reliability of the battery.    DETAILED DESCRIPTION - The method comprises (a) acquiring a state of charge relating to a level of charge of an accumulator battery (5), (b) measuring values of the temperature of the accumulator battery at a first state of charge and at a second state of charge which is different from the first state, (c) estimating the value of the temperature of the battery at a future third state of charge, as a function of the values of the temperature measured in step (b), and (d) controlling temperature of the accumulator battery using a control unit as a function of the value of the temperature estimated in step (c). The step (a) is carried out continuously or repeated at regular intervals of time. The steps (b) to (d) are repeated in a loop. The first, second and third values of the state of charge are predetermined according to the value of the state of charge of the battery at the start of charging or discharging of the battery. The step (c) is performed using a refined mathematical function which associates each state of charge and the corresponding temperature. The controlling step is carried out such that the temperature of the battery reaches a target value. The target value is determined as a function of one of the following parameters comprising outside temperature, the first value of the state of charge, the second value of the state of charge, the third value of the state of charge, charge or discharge information of the battery, average discharge time of the battery, and average charging time of the battery. An INDEPENDENT CLAIM is included for a car comprising an accumulator battery.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a car.    Car (1)    Driving wheels (2)    Electrical motor (3)    Inverter (4)    Accumulator battery. (5)