Trends in Vehicle Energy Storage Systems: Batteries and Ultracapacitors to Unite

There is growing awareness that electrochemical energy storage alone cannot meet the demanding vehicle propulsion applications and still retain design targets for cycle and calendar life. Add to this the sharp roll-off in advanced chemistry battery power capability at cold temperatures, the negative influence of deep discharging on cycle life and thermal instability initiated by high rates and no wonder existing energy management strategies opt for a higher engine auto-off frequency. As a consequence, today¿s vehicle traction battery is effectively throttled, realistic fuel economy capability curtailed and performance compromised. Visionary companies are already introducing ultracapacitor packs as power boosters in batteryelectric vehicles and as energy recuperators in micro-hybrids. This talk looks at these trends, makes an assessment of electrochemical storage systems and proposes that optimized energy and power components make more sense than further compromise in battery only energy storage systems.