The use of equalizing converters for serial charging of long battery strings

The authors present a technique that uses DC-DC converters to shunt energy from cells (or groups of cells) while the entire string of cells is being charged. The amount of charging of each cell can be controlled by varying the amount of diverted energy. The technique does not exclude the use of different capacity cells within the string nor exclude the use of different types of energy storage elements. If a cell fails, the converter across it will automatically regulate the voltage across the failed cell during charging and allow current to flow in the whole battery string. For energy discharge, the converters across the functional cells can be used in the traditional fashion with their outputs in parallel while the open-cell voltage is still maintained