CRADA Report

NREL/TP-7A1-48420

August 2010

Evaluating Ultracapacitors for the 

Saturn Vue Mild Hybrid Platform

Cooperative Research and Development 

Final Report

CRADA Number: CRD-08-00276

NREL Technical Contact: Ahmad A. Pesaran
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Cooperative Research and Development Final Report

In accordance with Requirements set forth in Article XI.A(3) of the CRADA document, this document is 

the final CRADA report, including a list of Subject Inventions, to be forwarded to the Office of Science

and Technical Information as part of the commitment to the public to demonstrate results of federally 

funded research.

CRADA number: CRD-08-00276

CRADA Title: Evaluating Ultracapacitors for the Saturn Vue Mild Hybrid Platform

Parties to the Agreement: General Motors + NREL

Abstract of CRADA work:

Recent analysis conducted by NREL for the USABC and the Electrochemical Energy Storage Technical 

Team indicated that HEVs utilizing smaller energy windows from the on-board storage system can 

achieve much of the fuel economy benefit realized by larger energy window HEVs. The simulations 

showed that nearly all hybridization fuel savings are realized with energy windows of 150 Wh or less. 

Dynamometer testing of a variety of production HEVs (both mild and full hybrid) has confirmed battery 

window use less than 200 Wh on standard drive cycles. These findings suggest a cost-saving opportunity 

from using either smaller batteries or ultracapacitors (which have lower projected long-term costs and 

superior cold-temperature performance) in order to still achieve a sizeable hybridization benefit. An 

additional limitation for batteries is that even a small in-use energy window requires a much larger 

nominal energy level in order for the battery to last the life of the vehicle. Ultracapacitors on the other 

hand possess excellent cycle life capability, so they require a much smaller size margin (even if they are 

frequently cycled over a smaller in-use energy window). With specific respect to the production Saturn 

Vue Green Line BAS Hybrid, NREL’s dynamometer test data analysis has indicated that the vehicle 

already uses energy windows no greater than roughly 50 Wh on each of the standard test cycles 

examined. This tentatively suggests that an ultracapacitor with approximately 75 Wh of usable energy 

could be used to achieve most if not all of the current configuration’s fuel savings—much smaller than 

the 600 Whr battery used in the current Vue hybrid.

Summary of Research Results:

• Accomplishments

– NiMH (stock)

– Converted and tested HEV with three energy storage configurations

– 1 and 2 Ultracapacitor modules

• Findings

•

– The HEV performed equal or better with one Ultracapacitor module relative to the 

stock NiMH HEV configuration

Significance

– Ultracapacitors possess excellent life and low-temperature performance, and have low 

long-term projected costs 

– Ultracapacitors could increase HEV market penetration (thus increasing fuel 

savings)

See attached publicly-presented summary for further details 

(Gonder_HEVUcapBatteryTesting_2010SAEHEVSymposium_FINAL.ppt).
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Subject Inventions listing: None

Report Date: 4/19/10 Responsible Technical Contact at Alliance/NREL: Pesaran, Ahmad A.

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