Method and apparatus of a modular management system for energy storage cells

A modular management system is described for balancing, testing and protecting rechargeable energy storage cells connected in series. Different energy storage cell technologies can be connected in the same battery pack and they can be completely balanced by using one or both of two balancing modes. In addition, the modular management system comprises of bidirectional and unidirectional switches optionally connected to a single ohmic device such as a resistor for i.e., passive/active balancing, and testing mode for SoH/SoC estimation, preferably without using any extra or external components (i.e., capacitor or inductor or DC/DC converter or power supply).