A process for maintaining the working temperature of a battery management system for maintaining the working temperature of a starter battery pack containing two or more battery cells of lithium-ion; lithium-iron-phosphate battery cells mutually connected in series and parallel, where the said system incorporates an unit for cell temperature management and measurement, and voltage measurement of each individual battery cell and for cell heating management, which unit in real time generates the temperature and voltage signals of the battery cells, characterized in that - the unit incorporates a temperature sensor mounted directly on one of the cells; a screen displaying the cell temperature data, the total and/or individual cell voltage; - furthermore, the said system contains data on a predefined upper temperature value t 2 and a lower temperature value t 1, and a push-button for manual activation or deactivation of cell heating; - where the working temperature of the battery cells is kept up by a heater (28, 23) in the form of foil pasted over the cells, or, in case of flat cells by a heater in the form of flat foil placed in between the cells or by a shared heater of any form inside the casing; and it involves the following steps: - input of data on the upper temperature value t 2 and the lower temperature value t 1; - input of data on permissible voltage drop value; - input of time interval data to detect the non-use of the battery pack; - checking whether the push-button for the activation or deactivation of cell heating is active or not; - if the push-button is active, the heating status of the battery cells will change and checking is done to determine if the heating function is on; - if the heating function is on, temperature t ' measurement of the battery cell and signal generation on measured temperature t'; - checking if the measured temperature t' is lower than the lower temperature value t 1, where, if the measured temperature t' is lower than the set temperature t 1, cell heating is activated; and - heating the cells and generating in real time the signals on temperature t ' of each of the battery cells until the cell temperature is equal to or higher than the upper temperature value t 2, after which cell heating is discontinued. - the unit incorporates a temperature sensor mounted directly on one of the cells; a screen displaying the cell temperature data, the total and/or individual cell voltage; - furthermore, the said system contains data on a predefined upper temperature value t 2 and a lower temperature value t 1, and a push-button for manual activation or deactivation of cell heating; - where the working temperature of the battery cells is kept up by a heater (28, 23) in the form of foil pasted over the cells, or, in case of flat cells by a heater in the form of flat foil placed in between the cells or by a shared heater of any form inside the casing; - input of data on the upper temperature value t 2 and the lower temperature value t 1; - input of data on permissible voltage drop value; - input of time interval data to detect the non-use of the battery pack; - checking whether the push-button for the activation or deactivation of cell heating is active or not; - if the push-button is active, the heating status of the battery cells will change and checking is done to determine if the heating function is on; - if the heating function is on, temperature t ' measurement of the battery cell and signal generation on measured temperature t'; - checking if the measured temperature t' is lower than the lower temperature value t 1, where, if the measured temperature t' is lower than the set temperature t 1, cell heating is activated; and - heating the cells and generating in real time the signals on temperature t ' of each of the battery cells until the cell temperature is equal to or higher than the upper temperature value t 2, after which cell heating is discontinued.