the actual measured data in some cases it may be advantageous that the length of the long buffer corresponds to the length of the individual drive segments the controller checks the current value of vehicle speed and the reads the contents of the short term buffer as shown in step 60 to detect the beginning and end of a drive cycle segment if a vehicle speed increase from zero is detected a new drive cycle segment is initialised as shown in step 62 by writing the previous buffer contents to matrix variable a and resetting the buffer as shown in steps 64 and 66 in a similar manner if a speed decrease to zero is detected as shown in step 68 a stopped segment is initialised if vehicle speed remains constant the data is appended to the data buffer as shown in step 69 every time a segment is initialised the contents of the buffer is written to memory as marc variable a tat is available for processing for other modules the next task within the control period is the system identification process 22 fig6 the objective of this process is to the at the mathematical model of the vehicle is representative of the current sate of the system it is well understood that the component characteristics particularly those of the electrochemical battery 4 or 14 are sensitive to temperature ageing operating history etc the system identification routine identifies current system parameters and updates.