Following the preview of the Daimler eCitaro bus in the spring in front of media representatives in Stuttgart, its world premiere took place a few days ago. In a cool hall atmosphere in the industrial area of Mainz I experienced the stage presentation: a revolutionized electric bus including a light show and technical lectures.
Daimler’s electric city bus, which now adds an’e’ to its name based on the bestseller Citaro, is the electric hope for Daimler’s urban public transport.

“It’s about transporting people,… we have a great responsibility and that’s why we never sacrificed speed to quality,” said Martin Daum, Member of the Board of Management of Daimler AG, responsible for Daimler Trucks & Buses, at the presentation. “We want electric commercial vehicles that function reliably under all conditions – in other words, at any outside temperature, any traffic density and any topography.

The eCitaro initially as a solo bus

The platform for the new Mercedes-Benz eCitaro electric bus is the world’s bestseller Citaro, Mercedes-Benz’s best-selling city bus with more than 50,000 units. The all-electric eCitaro is available in two and three-door versions as a solo bus. The articulated bus version is then scheduled for 2022. The new eCitaro is immediately recognizable by its unique design. However, the layout of the passenger compartment remains unchanged, so the familiar variants of seating and optional equipment can be selected as usual.

Much more than just a hi-tech bus

“We work with our customers to develop a concept that is compatible with their current telematics systems.” Before purchasing a new eCitaro, solutions are developed that include pre-terminating the eBuses, loading entire vehicle fleets and a detailed training system for the employees of the companies or municipal utilities. Finally, additional focal points must be taken into account for an electric bus. Handling the batteries alone requires training; the drivers themselves can make a significant contribution to the range of their vehicle with a trained driving style.

Up to ten battery modules, innovative thermal management

Speaking of batteries. These are of modular design in the eCitaro; six to ten battery packs with a combined maximum capacity of 243 kWh store electricity for the electric portal axle with two motors on the wheel hubs. As an alternative to the standard power supply via plug in the depot, a charging via current collector is optionally added after the start of series production. This can be done either via a vehicle-mounted pantograph on the roof or a stationary pantograph via charging rails on the roof.

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Daimler’s cautious approach to the range discussion

Prismatic cells are currently used. The current range of the eCitaro in summer is estimated at around 150 kilometres. Ideally, it should be as much as 250 kilometres. But the people of Stuttgart are now taking a cautious approach here. In view of the currently confusing discussions about the range of electric vehicles, Daimler has decided to draw customers’ attention to worst-case and best-case scenarios.

In fact, the power of the batteries is only sufficient for 110 kilometres in winter. Daimler has tested this in recent years at temperatures of -30 degrees Celsius and less during test drives in Finland. But as battery technology continues to evolve, this range will also increase.

Step-by-step procedure for the electric bus

Mercedes is thinking in stages here: in 2020, its own lithium-ion batteries will have a capacity of 330 kWh. This enables a reliable range of 200 kilometres. As the eCitaro is upwards compatible, these new batteries can be installed in existing vehicles.

In addition, the new head of Daimler Buses and CEO of EvoBus GmbH Till Oberwörder announced a real surprise. Solid batteries with an energy density of 400 kWh will be available for the eCitaro buses from 2020. However, the advantage of high energy density has its downsides: these batteries are not suitable for high-performance charging, i.e. changes in the charging infrastructure are necessary. From 2022, a fuel cell will then be able to extend the range by 400 kilometres. This means that more than 90 percent of all common routes for city buses can be covered.

Sophisticated thermal management in eCitaro

In my opinion, the thermal management of the eCitaro is particularly exciting. For those of our readers who are not involved in the daily energy management of buses, this is the only important information: a bus actually consumes more energy for the thermal in the vehicle than for the actual movement. The constant opening and closing of the doors during the many stops in summer and winter allows either heat or coolness to penetrate or escape.

The eCitaro’s newly developed air-conditioning system works with CO2 refrigerant, while a heat pump regulates the temperature in the passenger compartment. All heat-emitting components are networked with each other. The temperature control even depends on the number of passengers on board. Compared to the Citaro with combustion engine, the energy requirement for heating, ventilation and air conditioning is reduced by around 40 percent and the range increases in parallel. This is the finest German engineering.

With these features, the eCitaro of 2018 already covers around 30 percent of the requirements of transport companies without intermediate charging. As the development of battery technology is progressing rapidly, the concept of the eCitaro already envisages a switch to future battery technology. The next generation of the eCitaro will then already cover around 50 percent of all missions. With a nominal battery capacity of around 400 kWh in the solo bus and an even higher capacity in the articulated bus, the eCitaro will then cover around 70 percent of all requirements from 2020 without intermediate charging.

With the help of electric city buses, we will take a big step towards urban, more ecological mobility in the cities. With the eCitaro, Daimler shows that the Stuttgart company is meeting the challenges. I really prefer a manufacturer that is openly and gradually switching to electric buses with its customers. Ultimately, the acquisition costs for an eBus at around €500,000 are so significant that city superiors cannot replace all diesel buses in their inventory overnight. The first orders for Daimler’s current generation of electric buses are placed in Hamburg, Berlin and the Rhine-Neckar region. The quality and innovative strength of Daimler will ensure that these will not remain the only orders.

Image rights: Daimler AG Press Page, Michael Brecht