10. March 2022

Away from the standard: New test procedure for eBikes

The Darmstadt University of Applied Sciences, Department of Electrical Engineering and Information Technology, and ADP Engineering GmbH in Dieburg, Germany, are starting a joint scientific project to develop new range testing methods for eBikes. The long-term research project is led by Prof. Dr.-Ing. Christof Klesen at the university and Dipl.-Ing. Peter Böhm, Head of Development at ADP Engineering GmbH.

Status quo of reach measurement

The impetus for this project is the status quo of range measurement within and outside the industry: Up to now, the approaches have been rather confusing and imprecise, since a large number of individual methods are used and do not allow any comparisons. The standardized procedure is currently the so-called "R200 test", a basic test for determining ranges on a chassis dynamometer. In this test, a constant load is applied until the battery is empty. Subsequent calculations only yield a theoretical range, which has only limited significance and little proximity to practical use on the trail.

A special feature of the long-term cooperation between the university and the manufacturer is that bachelor's and master's students are closely involved in the project with their final theses.

Consider range influences more precisely

In order to be able to accurately compare current and future drive systems, an in-depth data analysis must be carried out. This includes taking into account all factors relevant in range measurement. These include the rider's weight and fitness level, pedaling frequencies, gear changes, terrain conditions, and also the various electronic components and special features of the respective e-bikes, such as weight and add-on parts related to the intended use. All of these points are to be considered as part of the project. The declared goal of the two cooperation partners is to be able to make meaningful performance comparisons of already available and future systems under standardized laboratory conditions.

To access the system's internal communications, the scientists use the e-bike's charging port to access the so-called CAN bus.

Cooperation great benefit

Development Manager Peter Böhm outlines the advantages and technical background: "Cooperation with universities has a long tradition for us and is a great benefit for us. This cooperation puts us in a position to collect a large amount of data in real-world operation on a scientific basis and thus obtain important information for independent developments." Using state-of-the-art tracking and data recording systems, the engineers will record real driving data in their field tests, which will then serve as the basis for laboratory conditions.

Prof. Dr. Klesen emphasizes the importance of the joint project for Darmstadt as a center of science: "In my view, it is a great advantage for our students if they already come into contact with practically relevant issues of their future professional life as engineers during their studies. With ADP Engineering, we have an ideal partner for this. The special feature of this cooperation lies in the intensive involvement of students at our faculty already in the conception and set-up phase of projects. For example, it was possible to lay the foundations for the test bench as part of bachelor's and master's theses in order to record real system data on the e-bike during the ride in field tests. One focus here, in addition to recording the usual system information, was the precise and GPS-supported recording of the switching intervals and the subsequent transformation of all this system information to the test bench."

At first glance, the test rig looks like many others. The essential difference, however, is that it can be used to transform real driving situations and conditions into the laboratory world.

In the meantime, the test stand in the Department of Electrical Engineering and Information Technology completed and ready for use. ROTWILD engineer Peter Böhm is pleased that further basic work can begin: "We are now faced with the extremely exciting task of recording real driving situations and conditions in order to transform them into the laboratory world, and we are looking forward to the findings for future e-bike developments."

Excited about the findings for future e-bike developments, the team around Prof. Dr.-Ing. Klesen and Dipl.-Ing. Peter Böhm.