Fast equalization for large lithium ion batteries

The use of lithium ion (LiIon) cells requires a battery management system to ensure that the LiIon cells can be operated safely and the battery pack will operate optimally. Lithium-ion batteries use an electrolyte that is flammable if exposed to high temperatures. Slight differences between the series-connected cells in a 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 because this would slightly overcharge some cells and would cause these cells to ignite. There are different methods used to ensure that the cells of a battery pack are not overcharged. The targeted equalizer (EQU) described here can be connected to any cell via a set of sealed relays to provide much faster equalization and higher efficiency than previous methods.