Performance and comparison of equalization methods for lithium ion batteries in series

Abstract

Deviations between batteries in series appear gradually and increase with the number of cycles. This inconsistency reduces the lifetime of battery packs, increases the cost of using them, and may lead to security issues. Equalization is an important means of reducing battery differences. The relevant research has focused on the design of equalization circuits and the improvement of equalizer efficiency while neglecting a comparative analysis of methods of equalization on the performance of battery packs, which hinders technicians from making the correct choice during application. A quantitative analysis is provided in this paper to compare the effects of methods of equalization on reducing the differences among batteries. Multiple parameters are introduced to describe differences among equalization methods, and the results indicated that equalization worked only at appropriate current rates and failed at large ones. With the same current rate in charging and discharging, the relative equalization time of active equalization was shorter than that of hybrid equalization. Active equalization was better than passive equalization in reducing

Prediction of Battery Return Volumes for 3R: Remanufacturing, Reuse, and Recycling

“…Although the equalization capability of the battery management system is capable of reducing the barrel effect and optimizing battery pack capacity, there are limitations in achieving the most effective remedy to cell inconsistency. Lv et al [25] show results for a SOC equalization strategy with a hybrid approach (passive and active equalization circuit) of series-connected topology during charging and discharging and were ultimately able to achieve the most effective result. Nonetheless, this result still ends up with an inconsistency range from ~8-10%, which is a significant amount in range performance reduction of larger battery packs.…”

Research on serial lithium‐ion battery alternating discharge equalization control systems

“…Passive equalization is straightforward and quick to operate, but because of its inefficient equalization, energy is not fully utilized and may be wasted 1,26 . Active equalization is more energy efficient than passive equalization because it uses active electronic components to transmit energy between battery units, but its complicated construction and control scheme prevent it from being applied widely 27 . To address these issues, this paper proposes an alternating equalization control system that connects a power switch with a single cell in series and parallel to form an equalization topology and its corresponding discharge control strategy.…”

“…1,26 Active equalization is more energy efficient than passive equalization because it uses active electronic components to transmit energy between battery units, but its complicated construction and control scheme prevent it from being applied widely. 27 To address these issues, this paper proposes an alternating equalization control system that connects a power switch with a single cell in series and parallel to form an equalization topology and its corresponding discharge control strategy. During the discharge process, the single cell that does not meet the discharge conditions is disconnected by the power switch, and the spare equalization battery is connected to discharge, achieving discharge equalization of the battery pack.…”