Lithium-ion battery pack arrays for lifespan enhancement

Depending on the application, power and energy requirements may differ significantly and, most likely, a single lithium-ion cell will not suffice. Battery packs offer cell interconnections that allow to obtain several possible voltage and discharge current ratings. Typically, the battery packs are designed to meet the specifications of the application within a certain range, and sometimes they are oversized just to consider degradation effects that may affect battery performance in the long term. However, operating a battery pack at different ranges for the state-of-charge and temperature, among other variables, might have a major impact on its lifespan. This paper, introduces a technique on how a modular battery pack can be designed in terms of extending the lifespan of the energy storage device, where each battery module has different capacity ratings. The available energy on each module of the battery pack is constrained and controlled to meet the electric demand, ensuring optimal ranges for the state-of-charge. Also, the article shows that it is possible to meet energy requirements with the modular battery pack at a lower cost than just a single module battery pack.