Daimler Buses develops fully electric coach drivelines

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Daimler Buses is working with a number of specialist and industry partners to develop prototypes of commercially viable electric coaches. DAIMLER BUSES

Daimler Buses is working with technical and operational partners to develop a commercially-viable long-distance coach within the next seven years

By the end of this decade, Daimler Buses says it intends to offer all-electric coaches through both its Mercedes-Benz and Setra brands. To accelerate development, Daimler Buses has teamed up with research institutes and experts from the industry to form the Electrified Coach project, abbreviated to ELCH and which is funded by Germany’s Federal Ministry for Economic Affairs and Climate Action.

Whilst city buses with an all-electric driveline such as the Mercedes-Benz eCitaro, are now a familiar sight on the streets of many German, European and worldwide cities, the picture is bleaker for long-distance operators. A search for electrically powered coaches tells a different story, and it is widely acknowledged that their development is far more challenging, with more hurdles to overcome before such coaches can be deployed. Requirements for long-ranges, flexibility in use, battery charging on the go, high payloads and space and weight capacity for large amounts of luggage are indispensable. Whilst there are some options available, no manufacturer has yet succeeded in developing a battery-powered coach that can cover workable ranges as well as availability for a wide variety of operating conditions on a par with a diesel vehicle, says Daimler Buses.

Head of Product Development and Production at Daimler Buses Michael Klein explained: “We are delighted to be the only bus and coach manufacturer able to bring our development expertise to the ELCH project. As a technological pioneer in the industry, we can deal with the topic both quickly as well as comprehensively and in a practical way.”

Modularity

The objective of ELCH is the development of a modular drivetrain and two emission-free and practical demonstration vehicles in the next four years, which will be tested under real operating conditions. Initially a modular drive system with a focus on energy consumption, range, driving performance and battery service life will be examined in the first concept phase. Synergies with components from Daimler’s truck division will also be taken into account.

In the second step, factors such as overall costs, environmental impact and possible integration into existing coach operating methods will be incorporated into the results. Based on an evaluation of the concept developments, two prototype drivetrains will then be produced and integrated into demonstration vehicles to enable testing under real operating conditions.

Daimler will take its findings from the construction of the demonstration vehicles and use them to form the basis for planning cost-effective production and assembly processes for electrically powered coaches, which it says will enable a fast production start-up in combination with a modular approach.

Daimler says it is aware that acceptance of the technology largely depends on its suitability in practice, which is something that will be recorded systematically for the first time in the project and serve as a reference for the design of the drivetrains. The project aims to ensure that the space required for installation corresponds as far as possible to current diesel coaches and buses, along with the permissable payload.

The potential profitability of the concept vehicle will also be assessed from the operator’s perspective and taken into account, to help Daimler identify cost-efficient concepts for individual vehicles and fleets of electrically powered coaches to suit various operating profiles. Test drives on real customer cycles will also form the basis for the further development of the drivetrains up to series maturity.

Although Daimler Buses is the coordinator of the project, other partners include the Karlsruhe Institute for Technology, the University of Mannheim Institute for Sustainable Energy Studies, the Technical University of Kaiserslautern’s Institute for Mechanical and Automotive Design and Flix, parent company of long-distance coach operator FlixBus.

Flix will contribute its experience in planning and controlling a long-distance coach network to the project. The operations of its current vehicle fleet will provide the data for deriving representative driving cycles for long-distance routes, and Flix will evaluate the operational characteristics of the projected solutions at an early stage in the project to offer feedback on the feasibility of switching to battery electric coaches. Flix will also be involved in the testing of the demonstration vehicles under real operating conditions; the operator sees the use of alternative drives as an important part of its strategy toward further CO2 reduction.

The Institute for Mechanical and Automotive Design (iMAD) and the Institute for Fluid Mechanics and Fluid Flow Machines (SAM) at the Technical University of Kaiserslautern will each contribute specific expert knowledge in the disciplines of lightweight construction and aerodynamics. The Karlsruhe Institute for Technology’s Institute for Information Technology will contribute its expert knowledge in handling large amounts of data to the analysis of operating conditions and the development of a smart operating strategy. In addition to minimising energy requirements, factors such as optimal load distribution of the drivetrain and the efficient use of energy recuperation will be taken into account using artificial intelligence methods.

Based at the University of Mannheim, the Mannheim Institute for Sustainable Energy Studies will carry out the profitability analysis from the perspective of the operators to ensure the marketability of coaches with battery-electric drivetrains. Daimler expects that the close co-operation and expert knowledge will allow the project to progress quickly to bring an electric long-range coach to market before the end of the decade.