Predictive performance estimation for a dual-battery system in mild-hybrid vehicles

Abstract. Continuously increasing requirements for on-board system performances lead to new topologies for the energy distribution in vehicles. One promising concept is the usage of a dual-battery system instead of the conventional lead-acid “starting lightening ignition” battery. As this system is not able to control the current share between the two batteries, its performance depends on the actual battery specific operating points.The initial conditions of state of charge, voltage level and temperature influence the current share and lead to a different voltage drop of the system. This paper yields to, the basic understanding of the current share between the two batteries. The conventional performance estimation method for standalone lead-acid batteries can no longer be applied to this system. Therefore, a new algorithm for the voltage drop calculation of the dual-battery system is proposed. Measurements at different temperatures, states of charge and voltage levels show the system behavior and prove the functionality of the algorithm.