Investigation of battery/ultracapacitor energy storage rating for a Fuel Cell Hybrid Electric Vehicle

Combining high energy density batteries and high power density ultracapacitors in fuel cell hybrid electric vehicles (FCHEV) results in a high efficient, high performance, low size, and light system. Often the batteries are rated with respect to their energy requirement in order to reduce their volume and mass. This does not prevent deep discharges of the batteries, which is critical to their lifetime. In this paper, the ratings of the batteries and ultracapacitors in a FCHEV are investigated. Comparison of system volume, mass, efficiency, and battery lifetime due to the rating of the energy storage devices are presented. It is concluded, that by sufficient rating of the battery or ultracapacitors, an appropriate balance between system volume, mass, efficiency, and battery lifetime is achievable.