When hearing that the battery cell capacity is insufficient, the first reaction should be to confirm whether there is indeed a problem of insufficient capacity. Simply put, first confirm whether the capacitor process is set incorrectly, such as high discharge current, short charging time of charging equipment, etc.
Does lithium-ion battery pack capacity affect driving range and dynamic ability?
Lithium-ion battery pack capacity directly determines the driving range and dynamic ability of electric vehicles (EVs). However, inconsistency issues occur and decrease the pack capacity due to internal and external reasons. In this paper, an equalization strategy is proposed to solve the inconsistency issues.
What factors affect the inconsistency of a lithium-ion battery pack?
The lithium-ion battery pack is a complex electrical and thermal coupling system. There are many factors affecting the inconsistency of the battery pack, which can be summarized into three aspects: the raw material, the manufacturing process, and the use process . 2.1. Difference in materials
Similarly, the battery pack cannot charge if cell 3 is fully charged. Overall, pack capacity can be formulated as (1) C P = m i n SO C i · C i + m i n 1 - S O C j · C j where C P is the pack capacity, SO C i, SO C j are the current state of charge, and C i, C j are the capacity of cell i or j.
However, the terminal voltage is influence by many factors, for example, capacity and internal resistance. A proper voltage difference is usually difficult to define. As a result, over-equalization occurs, and the energy of the battery pack is wasted. It is obvious that the capacity of the battery pack fails to be maximized.
The industry standard defines the consistency of lithium-ion batteries as the consistency characteristics of the cell performance of battery modules and assemblies.
In an active equalization, extra energy is transferred from cell to cell all the time, and the maximum pack capacity of the battery pack is the mean value of all cell capacities. This is expressed by Eq. (3) below. (3) C p = m e a n C i