Current research on State-of-Charge (SOC) tracking for rechargeable batteries focuses primarily on analyzing batteries consisting of a single cell, or otherwise treat a set of series-connected cells as a homogeneous unit. Yet, as the number of series-connected cells per battery increase, so does the challenge of ensuring safe and efficient operation over a potentially long period of deployment. Cell-level energy balancing is commonly proposed as a means to address the effects of cell property mismatch. However, no comprehensive solution exists addressing the need to maintain SOC accuracy over the full life of a large battery, while also managing the energy imbalance which develops between cells. If poorly managed, this imbalance can reduce usable capacity and lifespan. This paper proposes an integrated solution to these various issues by tracking SOC on a per-cell basis and applying SOC to a cell-balancing application. The effectiveness is demonstrated using a custom test platform.