However, battery balancing technology, a common configuration, often does not perform very well because if the capacity of a battery in series does not match that of the other batteries, it will reduce the capacity of the entire battery pack.
Capacity mismatch in lithium-ion battery balancing technology includes state-of-charge (SOC) mismatch and capacity/energy (C/E) mismatch. In both cases, the total capacity of an 18650 lithium-ion battery pack can only reach the capacity of the weaker battery. In most cases, the cause of battery mismatch is imperfection in process control and detection methods, rather than changes in the chemical properties of lithium ions themselves. Prismatic lithium-ion batteries require greater mechanical stress during production, making them more prone to differences between cells. Furthermore, lithium-ion polymer batteries can also exhibit differences between cells due to the adoption of new processes.
Battery balancing technology addresses SOC and C/E mismatch issues, thereby improving the performance of series-connected lithium-ion battery packs. Battery mismatch can be corrected by balancing the batteries during the initial conditioning process, after which balancing only needs to be performed during charging. However, C/E mismatch requires balancing during both charging and discharging. Although the defect rate may be low for a particular battery manufacturer, further quality assurance is still necessary to prevent issues such as premature battery life.
