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How Ultracapacitors Enhance Automotive Engine Start-Stop Performance

How Ultracapacitors Enhance Automotive Engine Start-Stop Performance

| Stefan Werkstetter, Systems Applications Engineering Manager

As automakers come under more pressure to reduce carbon emissions, the technologies that enable electrification to improve fuel economy become vital.

One of those technologies is ultracapacitor energy storage. Ultracapacitors, also called supercapacitors, have been integrated into millions of vehicles for the fuel-saving start-stop function, which shuts off the car’s engine during a stop and restarts the engine when the brake is released.

Today, millions of autos have incorporated ultracapacitor technology for this application since they are specialized for delivering short-term burst power. When integrated into a battery-based engine start-stop system, ultracapacitors relieve the car’s battery of high current, repetitive cycling that often shortens battery life.

The graphic below demonstrates how the ultracapacitor works in a vehicle for engine start-stop.

Batteries are configured to provide continuous low power for features such as the car’s heating and cooling, the radio and Internet service—features that require long-term energy at low to moderate power level. The ultracapacitors provide fast burst power for the starter, taking on this short-term, high power requirement of an engine crank.

The ultracapacitor system allows the starter to be separated from the 12-volt boardnet, thereby eliminating voltage sags (decreases in voltage during times of high power demand) and improving system-wide energy efficiency. In addition to fast, smooth engine starts, the ultracapacitors reduce engine vibration, thereby improving the driver experience.

Cars with internal combustion engines without start-stop systems will phase out in the near future. At that time, already entry-level vehicle platforms will be equipped with start-stop systems. Ultracapacitors serve both peak power and backup power requirements, contributing to system efficiency, reliability and an improved driver experience.

To learn more about automotive trends, check out What’s Trending In The Automotive World And How Energy Storage Fits In.

Mike EverettStefan Werkstetter
Systems Applications Engineering Manager
About this author

Stefan Werkstetter is systems applications engineering manager at Maxwell Technologies and is a state-certified electrical engineer with a focus on computer science. He has several years of experience in electrical systems pre-development, evaluation and testing. Prior to joining Maxwell, he worked in the automotive industry for a German original equipment manufacturer and as a technician in telecommunication electronics. On his free time, he enjoys hiking, camping, gardening and spending time with his wife and two sons.

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