Parallel lithium battery pack

Lithium batteries can indeed be connected in parallel, and this method is commonly used to achieve higher capacity and extend the runtime of a battery system. By connecting two or more lithium batteries with the same voltage in parallel, the resulting battery pack retains the same nominal voltage but boasts a higher Ah capacity.

According to the parallel principle, the current of the main circuit is equal to the sum of the currents of the parallel branches. Therefore, a parallel lithium battery pack with “n” parallel batteries achieves the same charging efficiency as a single battery, with the charging current being the sum of the individual battery currents.

Parallel connection attains higher capacity by adding up the total ampere-hour (Ah). Some packs may consist of a combination of series and parallel connections. Laptop batteries commonly have four 3.6V Li-ion cells in series to achieve a nominal voltage 14.4V and two in parallel to boost the capacity from 2,400mAh to 4,800mAh.

Parallel lithium batteries have many advantages, including increased capacity, enhanced power output, and improved overall performance. When multiple batteries are connected in parallel, their individual ampere-hour (Ah) capacities add up, resulting in a higher total capacity.

When designing a lithium battery pack, engineers have two primary options: connecting individual cells directly in parallel or connecting strings of cells in parallel. Each approach has its advantages and disadvantages, and the choice depends on the specific application needs and design goals.

To meet the power and energy requirements of the specific applications, lithium-ion battery cells often need to be connected in series to boost voltage and in parallel to add capacity . However, as cell performance varies from one to another [2, 3], imbalances occur in both series and parallel connections.