<p>Energy equalization technology prevent the cells series-connected in a battery pack from over-charging or over-discharging by balancing the state of charge of the cells. The capacity degradation of battery cells with different rates, which leads to inconsistent capacity, often occurs within aging battery packs, causing failure in balancing the state of charge with existing methods probably. This paper presents a model predictive control based equalization strategy for an aging battery pack with the series-connected cells of inconsistent state of charge and inconsistent capacity. This strategy takes state of charge as the equalization objective and establishes a state space model about the residual energy of battery. In addition, considering the nonlinear energy efficiency of the equalizer, a nonlinear model is presented to optimize energy loss and equalization time. This method can not only balance the state of charge of the cells in the battery pack, but also reduce energy loss and accelerate the equalization speed. Simulation results verify that this method can tackle the problem of imbalanced state of charge of cells in the aging battery pack with inconsistent capacity of cells, and improves time efficiency and energy efficiency.</p>