Battery Guard : Designing a Charging Station for E-bikes in Dutch Public Environments

Abstract: The e-bike trend is getting bigger and bigger all around the world, in Europe the number of new e-bikes sold during 2019 exceeded 3,5 million accounting for 17% of all bike sales (CONEBI, 2020). In the Netherlands it is more than a trend, e-bikes are everywhere and since 2018 there are more new e-bikes sold in the Netherlands than new regular bikes (Bovag, 2020). However, e-bikes charging anywhere poses potential risk since the batteries used in e-bikes are mostly li-ion batteries (Recharge, 2018). Li-ion batteries can get unstable due to several reasons, most common is that this happens during charging (Dutch fire department, 2018). This can lead to thermal runaway, that in turn can lead to battery fires and explosions (Kong et al., 2018). This master thesis has been carried out in collaboration with Deelfiets Nederland, a Dutch e-bike rental company, to develop a charging station that can provide safe charging of e-bike batteries in public spaces. The aim of this project is to investigate what guidelines, user needs, and prerequisites apply to the design of such a station. Through user research and literature studies the goal is to build a deeper understanding of the area of public e-bike charging while also making a product concept as ready for production as possible.  From user research as well as an extensive literature review, innovation opportunities and problems were found that together formed design criteria. Several creative methods have been used throughout the project to generate a lot of ideas to satisfy these criteria.  By conducting research on battery and charger sizes in combination with a lot of prototyping and letting users give feedback on the prototypes, a compact but still ergonomic way to store and charge batteries have been found. Since the target group consists of a lot of elderly people (65+) guidelines from ergonomic research have been followed to place boxes at heights where the elderly does not have to bend to reach the lowest box or reach over shoulder height to reach the top box.  It was found that the best way of making a charging station safe for public spaces is making sure that fires do not happen in the first place. Before thermal runaway, li-ion batteries release gases (Cai et al., 2021).  By charging batteries in metal boxes fitted with gas sensors thermal runaway should be able to be detected about seven minutes before it happens. By turning off the power to the battery when it is venting gases, thermal runaway could possibly be avoided (R. Bisschop, personal communication, Mars 22, 2021).