Hybrid energy storage system for conventional vehicle start-stop application

Ultracapacitors can provide high power density, high efficiency, and extended cycle life in various applications. Lead acid batteries, on the other hand, offer high energy density, low cost, and good performance in low temperature. In this paper, a hybrid energy storage device comprised of a Lithium-ion ultracapacitor module and a lead acid battery is modeled, built, and tested for the vehicular start-stop application. Hundreds of cranking events have been performed with the single lead acid battery and the hybrid storage and the performance of the systems have been evaluated and compared. Mathematical derivation, analysis, and a thorough energy storage aging study have also been conducted and presented.