Open Source Battery-Aging-Tool for the Lifetime Prediction of Battery-Packs with Respect to Uncertainties and a Distribution of Production Quality

openBat is an open source battery-aging-tool for the lifetime prediction of battery-packs composed of lithium-ion batteries. The aging tool comprises and electric, a thermal and an aging model. It is being developed within a publicly funded project by the Federal Ministry for Economic Affairs and Energy.

openBat can be used by companies, institutions and private persons free of charge and anonymously. The individual simulation results can also be used for commercial purposes. Publications of the results must include ISEA of RWTH Aachen University and the project website.


Over 600 single battery cells are being measured in the scope of this project to assess their aging behavior. The cells are being aged by various calendaric and cyclic tests. The collected data is also also available online and is the basis for the development of an aging model.

Cyclic aging

Electronics have been developed to collect the cyclic current and voltage aging data of 30 cells connected in parallel (see figure below). This enables the investigation of the impact of module topology and of parallel connected cells on aging.


A second set of electronics has been developed to assess calendaric aging. Five cells are being held at a constant voltage (e.g. 4.1 V) and a defined temperature (e.g. 35 °C). The residual current needed to keep the cells at the constant voltage is tracked continuously. This information combined with remaining capacity and electrochemical impedance spectroscopy is crucial for understanding the calendaric aging.



1st September, 2015 to 31st August, 2018






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