In a method of charging several electrochemical cells 5, 6, 7 connected in series, by a charger 1 which allows adjusting the voltage and the charging current, the voltage of each cell is detected permanently, and when a first cell reaches a predetermined threshold voltage, an increment of the charging current is applied to several cells 5, 6, 7 and simultaneously a shunt resistor of a current equivalent to the increment in the charging current of the several said cells 5, 6, 7 is connected in parallel to said first cell, and when each of the subsequent cells reaches the threshold voltage, a shunt resistor of a current equal to the increment in charging current of said several cells 5, 6, 7 is also connected in parallel to this cell. The invention is applicable to the use of accumulator systems for powering electric vehicles and thermal vehicles with self-contained electric mode.