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Electrical Storage
BMWi
Analysis 1.2.2016

Performance profile of a lithium-ion battery with consideration of micro-fluctuation
© Fraunhofer UMSICHT

Standardising performance tests

Researchers from Fraunhofer UMSICHT are designing performance tests for

battery storage systems. The tests are supposed to enable objective testing

and comparison of different types of batteries for standardised and

practical applications. Another goal is to apply these test cycles with a

real lithium-ion battery and with a lead-gel or a redox flow battery

for comparison.

Project status Project completed
Project duration August 2012 until January 2016

Performance tests for real stationary - and mostly grid-connected - application do not exist yet: for example a photovoltaic system on the roof with a storage like lithium-ion or redox-flow battery (battery types which will play a major role in the future). Thus, there is an ability missing to perform objective tests and make a statement about real life of the battery. The problem can be shown by the combination of a lithium-ion battery and a decentralized photovoltaic system.

  • Previously related, smoothed output profile of a lithium-ion battery © Fraunhofer UMSICHT
  • Performance profile of a lithium-ion battery with consideration of micro-fluctuation © Fraunhofer UMSICHT

In this application the highest possible self-sufficiency is desired due to the Renewable Energy Law in Germany (EEG). This application will lead to specific load profiles and various depths of discharge (DOD). The number of these mixed cycles a lithium-ion battery "survives" until degradation is neither known nor measurable with known test cycles. For this purpose, test cycles are developed, which include typical year-applications and reflect real fluctuations.

Testing performance and application

The main objective of this project is to design standardized performance tests for battery storages to compare different types of batteries for typecasted practical applications and objectively testing. A second goal is to apply these test cycles with a real lithium-ion battery and with a lead-gel or a redox flow battery for comparison. The project will run for three years and will end in July 2015. It is located at Fraunhofer UMSICHT.

The project "Standardized Performance Tests" consists of two main sections, one is research and development phase, the other is exemplary test phase. It is divided into seven work packages. The first four work packages include research, definition of application scenarios, investigation of micro-fluctuation and development of standard cycles. The other packages include practical battery tests.
Milestones are set for each year of the project. In the first year, this is the definition of application scenarios. The second year, aims to define the standards and last year the implementation of the battery test is defined as a milestone.

Performance and efficiency tests as well as the question of the stability and life cycles (State of Health: SOH) of electric storages are necessary to compare types of batteries to investigate various systems in terms of their suitability for particular applications. These performance tests are not yet defined. Up to now there are only pure capacity tests (Ah) for lead-acid batteries and nickel-cadmium batteries. And this is just a standard discharge, when the battery is discharged until 80% (80% DOD: Depth of Discharge).
In this project, performance tests will be developed, which do not exist previously. Without these tests, an objective comparison and an objective economic assessment of the batteries are not possible.

Neutral environment creates comparison

This project is not aimed at the optimization of existing storages, but creates a foundation for later loading optimization of chemical storages. The goal of the project is to create a neutral environment for comparing batteries. In the long term these cycles provide a contribution or they can even be the basis of a national/international standardization. The economic viability of storing is not the focus of this project, because at first standards are set.

If these standards exist, it will be easier to compare the different types of batteries or the products of different manufacturers, which also makes predictions for the economic viability clearly.

Supported by: The Federal Government on the basis of a decision by the German Bundestag

Dates

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Addresses

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Infobox

Research funding

The information system EnArgus provides information on research funding, including on this project (German only).