New technical features, the demand for fuel economy, and the potential to reduce production and operational cost are leading to additional and more powerful electrical consumers and making the overall electrical demand in vehicles increase. Vehicle electrical architecture is performing an evolutionary change to improve the efficiency of production, distribution, control and storage of electrical energy in the vehicle. New battery designs with performance patterns designed for the new architectures are needed, and some of the new demands may even exceed the capability of lead/acid batteries. Single and dual battery systems offer a wide variety of applications when combined with intelligent means to keep the batteries in an appropriate operational window. Detection of state-of-charge (SOC) and state-of-health (SOH) is essential to help the battery to fulfil its role as a key element for vehicle functionality and safety.