Battery packs consists of several smaller cells that can drift apart from each other and cause imbalance to the system. These imbalances can be balanced by either dissipating some energy (passive method) or redistributing the excess energy between the cells (active method). In this project they energy efficiency and balancing speed of two active method is investigated and compared to a traditional passive balancing method for 9 cells connected in series. The two active method investigated is the delta structured switched capacitor (DSSC) and chain structure switched inductor (CSSI) method. These methods have the ability to balance any cell with any other cell at any time, which, given the same initial imbalanced cells, results in a much faster balancing speed compared to the passive method.   The energy efficiency and balancing speed was investigated further by examining the energy gained when continuously charging and discharging the cells to model real drive cycles of the cells. This resulted in energy saving corresponding up to 5 Wh more energy per cycle after simulating for about 1900 cycles. This energy gain started however after 1000 cycles due to small imbalance between the cells. The energy gain of the active methods are however not sufficient enough to compensate for their higher component cost when considering the whole life of the cell. However, looking only the second part of the cell’s life, cycled more than 1000 cycles, the energy gain became more clear and the DSSC method start to be more beneficial to use.