Detachable Lithium-Ion Starter Battery and Analog Battery Management System for ICE Vehicles

Abstract

Continuous addition of electrically powered peripherals in vehicles has created a need for a more efficient and reliable power source that can replace conventional starter lead-acid (Pb-Acid) batteries. Due to their high energy-to-weight ratio, Lithium-Ion (Li-Ion) batteries can act as a potential alternative to the Pb-Acid batteries used in cars for engine ignition. However, it is not possible to use Li-Ion batteries as a drop-in replacement of Pb-Acid batteries due to differences in internal resistance and voltage thresholds for charging and discharging. In addition, Li-Ion batteries require balancing of cell strings connected in series whereas Pb-Acid batteries manage cell balancing during charging near full charge. To use Li-Ion cells as a battery pack, it is necessary to install a battery management system (BMS) that keeps the voltages of each cell balanced. This paper proposes a new design methodology for a scalable BMS that employs active balancing using analog discrete components. The analog control system of a BMS integrated with a DC-DC bi-directional Cuk converter allows increased reliability and efficiency. For a comparative analysis, balancing of the Li-Ion battery pack is also performed by implementing a digitally controlled BMS, and the results are compared with the designed analog BMS. Finally, an architecture comprising a DC-DC boost converter is also introduced to manage control over battery charging through alternator of the internal combustion engine (ICE) vehicle.