Highlights A parallel configuration of cells generates self-excited current oscillation The parallel battery system is shown to be convergent, stable, and robust Long-term trajectory in repeated cycles is enveloped in a closed orbit Warnings are given about capacity loss, possible current overload, and malfunctions.
3.4.2. Individual Cell Battery Parallel into the Battery Pack For a parallel-connected battery pack, the negative feedback formed by the coupling of parameters between individual cells can keep the current stable before the end of charge and discharge.
For parallel-connected battery cells, Offer et al. [ 16] tested a lithium-ion battery pack in a vehicle environment and reported that different inter-cell contact resistances can cause currents to flow unevenly within the pack, leading to cells being unequally loaded.
What happens if a lithium-ion battery is connected parallel?
Uneven electrical current distribution in a parallel-connected lithium-ion battery pack can result in different degradation rates and overcurrent issues in the cells. Understanding the electrical current dynamics can enhance configuration design and battery management of parallel connections.
To maximize battery pack capacity under space and cost constraints, battery cells are often connected in parallel to form battery strings, which become the building blocks for battery modules or packs [ 3].
How many cells are in a battery pack?
For example, the battery pack of a Nissan Leaf EV consists of 192 cells, with two cells in parallel; for a Chevrolet Volt PHEV, the battery pack is made of 288 cells, with three cells in parallel, to meet the 350-V system voltage requirement, .
Why are parallel lithium-ion battery modules important?
Parallel lithium-ion battery modules are crucial for boosting the energy and power of battery systems. However, the presence of faulty electrical contact points (FECPs) between the cells often leads to severe performance degradation, including reduced capacity, accelerated aging, and the potential risk of thermal runaway.