A smart automotive battery electrical energy storage device-system with built-in backup power. The battery has a primary power unit and a booster power unit which may reside in the same enclosure as that of the primary power unit and primary power unit and a booster power unit are electrically isolated most of the time. The primary power unit and a booster power unit are electrically connected intermittently when certain conditions are sensed. The battery has an electronic control unit with wireless transceiver electronic element. The booster power unit can be connected to the primary power unit using a smartphone application. The nominal voltage provided by the booster power unit can be same, higher or lower than the nominal voltage provided by primary power unit. Each of the primary power unit and booster power unit is comprised of multiple individual battery cells.