Battery Management Systems for Large Lithium-Ion Battery Packs
Section 1.3.2 Addenda
In batteries for aerospace applications, which must have an extremely high reliability, matched cells and a much simpler BMS are used.
The battery manufacturer tests multiple manufacturers and cells to select a batch of cells of high performance and reliability. Then, the manufacturer characterizes thousands of cells from that batch, and from that batch selects a group of cells that have perfectly identical characteristics (especially capacity, resistance and self discharge). Finally, the manufacturer balances those cells and assembles them into a battery.
Because the cells are identical, and they all start at the same SOC, it becomes a relatively safe assumption that all the individual cell voltages will remain in lockstep throughout the life of the battery. Therefore, a much simpler (and more reliable) BMS can be used, which only monitors the total battery voltage.