Southwest Research Institute (SwRI) recently acquired an extended range electric vehicle to include its batteries in the Energy Storage System Evaluation and Safety (EssEs) Consortium. (Earlier post.) The acquired vehicle is powered by an electric motor with electricity stored in a 16-kWh lithium-ion battery pack.
The Energy Storage System Evaluation and Safety (EssEs) consortium is a cooperative research project the mission of which is to provide transparency in the automotive battery market as a means to advance the development of energy storage systems for electric and hybrid-electric vehicle applications. EssEs intends to deliver on the mission by:
developing pre-competitive detailed cell-level test data on currently available electrochemical storage systems across a diverse number of manufacturers and products; and
performing research to advance the testing methodologies used to benchmark batteries, making tests faster, cheaper and more significant.
The four-year consortium, renewable annually, is designed to provide transparency in the automotive battery market to advance global development of energy storage systems. EssEs now has 11 participants. Information obtained through evaluation of the batteries in the plug-in will be included in the EssEs database that is available to all members.
The proposed test sets are categorized into four main groups:
Performance and Characterization: static capacity; constant power discharge; hybrid pulse power (low and high current levels); self-discharge; and cold cranking.
Life Cycle: combined life cycle testing and calendar life.
Abuse: thermal stability; overcharge; over-discharge; soft short circuit; hard short circuit; crush; penetration; electrolyte vapor analysis; and shock.
Manufacturing: mass variance; initial internal resistance; and open circuit voltage after extended storage.
The full test schedule is designed to accommodate 8 different battery type sets for life and abuse and 16 cell types for characterization per year. The testing includes multiple cells under different configurations and repeated testing for each cell type. Life cycle and performance environmental test conditions, including temperature, and specific cell configurations, will be recommended but will be determined by consortium members.
Test data, such as that from the new extended range electric vehicle, will be critical to the future of electric, hybrid electric and plug-in hybrid electric vehicle technology.—Dr. Bapiraju Surampudi, a principal engineer in SwRI’s Engine, Emissions and Vehicle Research Division who leads the consortium
SwRI notes that one of the advantages of joining the EssEs consortium is to gain access to battery evaluation data that is otherwise difficult to obtain. In some cases, as it is in the newly acquired vehicle, batteries alone are not available, and suppliers are reluctant to provide them for evaluation.
The test data produced by the consortium frees up testing resources of original equipment manufacturers, allowing them to concentrate on product development rather than performing individual battery cell assessments. Additionally, a non-disclosure agreement, specifying no sub-cell-level testing, is established with all cell manufacturers participating in the consortium.
To advance testing methodologies for benchmarking batteries, research is being performed to make tests faster, cheaper and more significant. The program is providing data from performance, abuse, life and consistency of manufacturing tests for member-selected sets of battery cells in a private, independent third-party laboratory format.
Consortium membership allows for equal cost sharing among the participants. Members receive semi-annual progress reviews, FTP secure server database access to monthly progress reports, annual program reports and full test results for each battery type per year.