When shipped to the reuse company, historical information of the retired battery systems, including manufacturers, models, batches and dates of production, types of batteries (nominal capacities, nominal voltage, chemistry, etc.), operation history, and reasons for retirement (reaching EOL, damage, safety concern, etc.), should be registered.

The entire battery module is torn down, and individual battery cells are obtained. For this purpose, multiple steps in a proper sequence have to be carried out to remove the components and fasteners.

All the steps after the disassembly are usually referred to as "screening, sorting, and classifying." The overall purpose of these steps is to screen out the cells that cannot meet the requirements of second-life applications and regroup the batteries with a close level of degradation and similar electrochemical performances.

With data from assessment tests, it is now possible to sort and regroup batteries according to their performance. The major task is to reduce the cell-to-cell (and module-to-module, if reused at a module level) variations, which are harmful to the battery life.

Specific control and energy management strategies are necessary to deal with the low energy and power capabilities, large inconsistencies, and potential safety concerns when integrating retired batteries from different EVs into a single stationary ESS.