A targeted equalizer for lithium ion battery packs

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. An electronic equalizer (EQU) must be used to balance the cell voltages individually since these batteries cannot be trickle charged like a lead acid battery. This is because even a slight overcharge can cause these cells to ignite. The targeted 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. This method has proven to be quite simple and very reliable due to the extremely long lifetime of this type of relay.