Fast equalization for large lithium ion batteries

Abstract

Slight differences between the series connected cells in a lithium ion (LiIon) battery pack can produce imbalances in the cell voltages, and this greatly reduces the charge capacity. These batteries cannot be trickle-charged like a lead acid battery since this would slightly overcharge some cells and may cause these cells to ignite. Therefore, an electronic equalizer (EQU) should be used to balance the cell voltages individually. The targeted EQU described herein can be connected to any cell via a set of sealed relays to provide much faster equalization and higher efficiency than previous methods.