Implementation of Charging Equalizer with Master-Slave Method on Lithium-Ion Batteries

A lithium-ion battery is widely used in various applications because of its high energy density, long durability, easy maintenance, and more eco-friendly than other battery types. To get appropriate voltage in the lithium-ion battery, a serial circuit could be applied. However, it needs more care in every cell voltage because using it continuously causes different voltage in every cell that will bring to undercharging in a cell. In different voltage conditions, the charging process will take different times to reach maximal capacity. If that condition is allowed, it will cause overcharging in the battery cell. So, this research brings charging equalizer method with master-slave mode in order to make every cell could be charged at the same time without any worry of overcharged and undercharged in one of the cells. Two flyback converter topologies are used in an application with step down and step up mode and both efficiencies are 79.32 % and 78.36 %. The result approved that the equalizer works properly, with the maximal different voltage of every battery is 0.01 V. The time of the equalization process is based on the voltage difference between cells.