Li-ion battery pack series-parallel topology:
1, The typical connection methods of Li-ion battery pack are parallel then series, series then parallel, and mixed connection.
2, Li-ion battery pack for pure electric bus usually adopts the connection method of parallel first and then series.
3, Li-ion battery packs for grid energy storage are often connected in series followed by parallel.
The advantages of Li-ion battery first parallel and then series
Li-ion battery single cell failure automatically withdraws, except for capacity reduction, which does not affect the use after parallel connection.
Parallel connection of a single lithium battery short-circuit caused by the parallel circuit current is very high, usually add fuse protection technology to avoid.
Disadvantages of Li-ion battery first parallel and then series
Due to the difference in the internal resistance of lithium battery cells, uneven heat dissipation, etc. will affect the cycle life of the lithium battery pack after parallel connection.
Advantages of Li-ion battery series first and then parallel
According to the capacity of lithium battery monomer first in series, such as 1/3 of the capacity of the whole group, and finally in parallel, which reduces the probability of failure of large-capacity lithium battery module; series first and then parallel is good for the consistency of lithium battery pack.
From the perspective of the reliability of the Li-ion battery pack connection and the trend of voltage inconsistency and performance impact, the parallel first and then the series connection is better than the series first and then parallel connection, and the Li-ion battery topology of series first and then parallel is beneficial to the detection and management of each Li-ion battery unit of the system.
