Method for balancing a battery and battery management system implementing such a method

The system has an activation unit for activating an active balancing circuit by switching a switching circuit (18) that interconnects a rechargeable element (12) e.g. Lithium-Ion element, of an electric storage battery pack (10) to a power supply device (20), where energy of the device produces individual balancing of the element. A cell of the element is connected in series with other cells of the pack so that a power circuit is not cut. The switching circuit is activated when the voltage to the element does not reach a predetermined value of the minimum threshold. An independent claim is also included for a method for balancing an electric battery.