LiPo battery cell tester for electric cars

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Dr. Hamar János Krisztián
Department of Automation and Applied Informatics

My final project is about the design, realization, and testing of a cell tester device which will be used by the BME Formula Racing Team. Measurements on two different accumulator cells with this device is also included in this paper.

The aim of the measurements is to decide whether the tested cells can be peak charged at higher current rates than according to its datasheet without significant capacity loss. The maximum peak current rate was determined by the leadership of BME FRT. The process of the validation measurements was specified by the cell manufacturer.

Based on these specifications two circuits were created. The first is a peak charger which is able to charge a cell with 80A for a short interval(<1s) and between two charging intervals, there is a relaxation interval(10s<). These two intervals together are considered as a cycle. The other one is a capacity tester.

Before the start of the design process, studying technical literature and market solutions for different cell types and testing methods were necessary. Then a detailed design of the circuits confirmed by simulation was done. This was followed by the realization of the cell testers including the software of the microcontroller. After testing the completed circuits, the specified measurements were executed and evaluated.

Finally, based on the experiences gained from the design and testing processes the concept of a universal cell tester was created. In the future, this device will be able to provide more information about the cells which makes possible a more sophisticated cell selection for the BME Formula Racing Team.


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