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Current and historical reports with sources

Hanna Kretz achieves Bachelor's degree at TU Chemnitz

Hanna Kretz, a student employee at BeST, has successfully completed her degree in "Sensory and Cognitive Psychology" with the grade "very good". Congratulations on the excellent result! The oral examination with presentation took place on Thursday, 22 June 2013 at the Technical University of Chemnitz.

Her work is entitled "Development of a sensor system to determine the electrochemical behaviour of NiMH batteries and optimisation of energy efficiency". Investigating the behaviour of rechargeable batteries is relevant for the use of IoT (Internet of Things) modules at BeST.

Hanna Kretz is studying at the Department of Physics, Experimental Sensor Technology at Chemnitz University of Technology under Prof Ulrich Schwarz:

Oliver Völckers participated in the audit as an evaluator.

Bachelor Arbeit Hanna Kretz

Summary (translated by DeepL)

"In this bachelor thesis, the differences between the voltage curves, battery capacities and discharge runtimes of continuously and intermittently discharged nickel-metal hydride (NiMH) batteries are analysed. Until the paper by Narayanaswamy et al. 2016 brought new insights, several studies were published (e.g. Zhang and Chakrabarty 2002 and Chau et al. 2010) that claimed to have found the recovery effect (more available energy during intermittent discharge) in secondary batteries. Only Narayanaswamy et al. 2016 refuted this effect. No significant difference was found between continuous and intermittent discharge for NiMH batteries. These measurements were replicated and verified in this bachelor's thesis. For the study, 15 measurements were carried out with 6x AA NiMH battery packs, in which the batteries were discharged intermittently with different frequencies and discharge-recovery ratios or continuously with different discharge resistances.

A sensor system with an Arduino Mega 2560 was planned for the measurement, circuit boards for the various measurements were soldered and the software for the microcontroller was developed. The results showed no significant differences between the two discharge strategies. As various systematic and relative errors occurred, the measurement results are not reliable. Nevertheless, the results from the paper by Narayanaswamy et al. 2016 were confirmed in principle, as a measurement similar to that in this bachelor's thesis was carried out there. In order to obtain more meaningful results, a study is recommended that contains more measurements and that implements the proposed solutions for the sources of error that occurred in this bachelor's thesis."


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