Quickly loaded – quickly back in the saddle

The Karlsruhe Institute of Technology (KIT) is developing a new charging method for e-bikes together with the e-bike manufacturer Coboc. This should allow the battery to be ready for use in less time.

Illustration of an e-bike

Battery charging times are also important for e-bikes. A fast-charging system could increase usage.

Photo: Keport / Panthermedia.net

Most e-bike riders are on shorter trips. In city traffic, you can get along well with the short range. This provides a small battery that takes up neither much space, nor the bike significantly complained. So far, every cyclist who needs more range, had to accept a large and heavy battery on the bicycle frame. Charged in no time, however, is neither the small nor the large battery. You should plan for two to four hours in any case. Researchers at the Electrotechnical Institute of KIT and the e-bike manufacturer Coboc are currently working together on a fast charging system for e-bikes. On the one hand, this should be compact and efficient, and on the other user-friendly and environmentally friendly.

The basis of this new process is lithium-ion cells. They offer several advantages: from long life to a short charging time. Lithium-ion cells have a high energy density, are sealed and therefore versatile. They tolerate a higher energy during charging, their discharge rate is very low. With up to ten amps, the batteries can be charged. This makes it possible to charge via the conventional household socket with 230 volts. After less than an hour, the lithium-ion cells should be fully charged again, so the researchers. Cyclists who use an e-bike would be ready to drive faster.

New fast charging system with diagnostic function

In addition to the high-performance lithium-ion cells, the developers also want to include a diagnostic function in the battery management system , This should allow an analysis of the batteries while using the e-bike. The e-bike manufacturer Coboc hopes that data will give him more information about the state of charge of the battery, the so-called state of charge (SOC) and the overall condition compared to a new battery, the so-called State of Health (SOH) , These two values ​​are based on each other. The data are measured during the use of the e-bike. Software developed for the Internet-of-Things, IoT for short, enables the collection of data. Afterwards, they should be analyzed and stored in the manufacturer’s internal Coboc cloud.

The developers want to make the results available not only to the manufacturer but also to the drivers of e-bikes. For this they are processed graphically. The manufacturer Coboc expects it to be a continuous development of e-bikes. Up-to-date information about the battery status is supposed to enable predictive maintenance. David Horsch, Coboc’s managing director, emphasizes that such a smart system can also make for more sustainability.

Lithium ion cell tested by KIT researchers.

At The researchers at the KIT rely on the particularly fast-paced lithium-ion cells in the fast-charging system.

Photo: Lea de Biasi / Steffen Jokisch, KIT

Bike to power tool

Lithium-ion battery is a generic term. It is available in different variants, and depending on the combination of materials it shows different properties. Originally, these batteries were mainly installed in small – especially portable – devices with high energy requirements. These include camcorders, digital cameras, mobile phones, notebooks, tablets and flashlights. In the meantime, the area of ​​application extends far beyond that. The batteries are found in electric cars, e-bikes and hybrid vehicles. They have made a decisive contribution to electromobility. In addition, they are used in electric wheelchairs, in model aircraft, in power tools such as cordless screwdrivers and in garden tools. Even battery storage power plants use lithium-ion batteries as energy storage. Modern solar systems, which convert the power of the sun into electricity, are also equipped today with storage units, which mainly consist of lithium-ion batteries.

KIT researchers are selecting in the project which lithium-ion batteries Cells from their point of view, and evaluate them. Afterwards, they examine the selected cells for their lifespan. The development of the rapid charging process and the diagnostic system is also one of her tasks. The manufacturer Coboc takes care of the requirements analysis, the development of the Operating management system, the installation of the IoT system in the in-house system – including all necessary hardware and software conversions – and their integration in the electric bicycle.

The Federal Ministry for Economic Affairs and Energy (BMWi) is supporting the project as part of the Central Innovation Program, which runs until the end of September 2021.

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