System for assisting the start of an electrically powered vehicle, comprising: - a battery for powering the vehicle, and - a processing means characterized in that the processing means are configured to: a) receive a sequence of voltage measurements (x i0, x i1, x i2,...; 0≤i≤n) by a sensor connected between the high voltage terminals of the battery and a vehicle chassis; b) compare the sequence of voltage measurements (x i0, x i1, x i2,...; 0≤i≤n) received from the sensor with previously established voltage patterns (P0, P1, P2,...), wherein each voltage pattern (P0, P1, P2,...) is formed by a sequence of voltage values (p i0, p i1, p i2,...; 0≤i≤n), and wherein each voltage pattern (P0, P1, P2,...) is associated to an insulation resistance value (Ri; 0≤i≤n); c) select the voltage pattern (Pi; 0≤i≤n) whose voltage values (p i0, p i1, p i2,...; 0≤i≤n) are closest to the voltage values of the sequence of voltage measurements (x i0, x i1, x i2,...; 0≤i≤n) received from the sensor; d) establish the insulation resistance value (Ri; 0≤i≤n) associated to the selected voltage pattern (P0, P1, P2,...) as the insulation resistance value of the battery; and e) enable starting of the vehicle if the insulation resistance value obtained exceeds a predetermined insulation resistance threshold value that ensures insulation of the battery. - a battery for powering the vehicle, and - a processing means characterized in that the processing means are configured to: a) receive a sequence of voltage measurements (x i0, x i1, x i2,...; 0≤i≤n) by a sensor connected between the high voltage terminals of the battery and a vehicle chassis; b) compare the sequence of voltage measurements (x i0, x i1, x i2,...; 0≤i≤n) received from the sensor with previously established voltage patterns (P0, P1, P2,...), wherein each voltage pattern (P0, P1, P2,...) is formed by a sequence of voltage values (p i0, p i1, p i2,...; 0≤i≤n), and wherein each voltage pattern (P0, P1, P2,...) is associated to an insulation resistance value (Ri; 0≤i≤n); c) select the voltage pattern (Pi; 0≤i≤n) whose voltage values (p i0, p i1, p i2,...; 0≤i≤n) are closest to the voltage values of the sequence of voltage measurements (x i0, x i1, x i2,...; 0≤i≤n) received from the sensor; d) establish the insulation resistance value (Ri; 0≤i≤n) associated to the selected voltage pattern (P0, P1, P2,...) as the insulation resistance value of the battery; and e) enable starting of the vehicle if the insulation resistance value obtained exceeds a predetermined insulation resistance threshold value that ensures insulation of the battery. a) receive a sequence of voltage measurements (x i0, x i1, x i2,...; 0≤i≤n) by a sensor connected between the high voltage terminals of the battery and a vehicle chassis; b) compare the sequence of voltage measurements (x i0, x i1, x i2,...; 0≤i≤n) received from the sensor with previously established voltage patterns (P0, P1, P2,...), wherein each voltage pattern (P0, P1, P2,...) is formed by a sequence of voltage values (p i0, p i1, p i2,...; 0≤i≤n), and wherein each voltage pattern (P0, P1, P2,...) is associated to an insulation resistance value (Ri; 0≤i≤n); c) select the voltage pattern (Pi; 0≤i≤n) whose voltage values (p i0, p i1, p i2,...; 0≤i≤n) are closest to the voltage values of the sequence of voltage measurements (x i0, x i1, x i2,...; 0≤i≤n) received from the sensor; d) establish the insulation resistance value (Ri; 0≤i≤n) associated to the selected voltage pattern (P0, P1, P2,...) as the insulation resistance value of the battery; and e) enable starting of the vehicle if the insulation resistance value obtained exceeds a predetermined insulation resistance threshold value that ensures insulation of the battery.