The locally emission-free, all-electric city bus combines innovative technologies with the genes of the Citaro, which has proven itself thousands of times over

• Distinctive original design
• New NMC 3 high-performance batteries for the eCitaro
• Long range, individual battery equipment, enormous increase in capacity
• Priority: Depot socket charging, optional opportunity charging
• Innovative thermal management drastically reduces energy consumption
• Cockpit and operating concept similar to the conventionally powered Citaro
• The unrivaled safety of the eCitaro
• E-mobility system: Comprehensive advice and service when switching to electromobility

The current version of the Mercedes-Benz eCitaro with third-generation lithium-ion batteries (NMC 3) is also at the highest level for city bus electromobility. It combines the Citaro’s thousand-fold proven platform with modular battery, charging and drive system technology, a functional yet attractive design and an unrivaled level of safety. It is also embedded in a comprehensive e-mobility system. All of this has led to the Mercedes-Benz eCitaro having long since advanced to the model of success among electric buses. In 2022 alone, almost 300 new eCitaro vehicles were registered in Germany – almost half of all newly registered e‑buses over eight tons. Almost 700 eCitaro vehicles are currently being operated by German public transport companies, with almost a quarter of these being articulated buses.

Distinctive original design

Launched in 2018, the eCitaro is based on the Citaro with a combustion engine and combines its proven city bus technology with a state-of-the-art electric drive. This is also reflected in the characteristic design of the eCitaro, which skilfully combines the familiar look of the Citaro with independent functional and design elements.

This is particularly evident from the "face" of the eCitaro. The main feature is the large Mercedes star, from which decorative elements radiate to the left and right. The star and decorative elements as well as the Mercedes-Benz brand insignia are embedded in a high-gloss black front mounting plate. LED individual headlamps have also been integrated into the component. The model lettering with a blue “e” indicates the all-electric drive technology discreetly and unmistakably.

The bumper and the three-dimensional A0 pillars typical of the model frame the face of the eCitaro. Another feature of the city bus is its curved windshield. The black glossy front mounting plate gives the vehicle a visually elongated appearance, allows it to rise elegantly up to the roof and incorporates the destination display. The windshield blends seamlessly into the roof via dark strips on the left and right side. In the middle, the roof supports a virtually floating “island” in the color of the vehicle. It is not only a visual feature but also forms the mouth of the roof cover.

The eCitaro’s roof structures are concealed behind an elegant roof edge elevation. It consists of a multi-part extruded aluminum profile. The glossy black bottom segment extends the lush side glazing of the city bus. The top segment is finished in the color of the vehicle, runs smoothly into the A0 pillar at the front and into the corner pillar at the rear and visually encloses the side. These visual tricks give the eCitaro appealing proportions and make it seem lightweight.

The rear corner pillars flow at the top with a strong curve in the roof edge elevation. Their elegant shape and the island that is also suggested here as a trim for the roof structures along with the black bars as a connection between the rear window and roof also make the high body seem lighter. The eCitaro features the rear lights as well as the tailgate and bumper from the current model range.

These components demonstrate that the eCitaro is really practical. It adopts the structure of the current model unchanged, thus ensuring straightforward repair in the event of accident damage. The curved windshield has been transferred from the Citaro Ü and is therefore a common spare part. The side roof edge elevation is segmented, which means it can be removed in individual parts and makes it particularly service-friendly. Important in daily practice for bus drivers: Despite the changed front section, all viewing angles and mirrors are identical to the Citaro. This makes it easy to quickly switch between the different versions.

New NMC 3 high-performance batteries for the eCitaro

The all-electric Mercedes-Benz eCitaro low-floor city bus with the latest NMC 3 batteries has been available since the end of 2022. Daimler Buses is once again allowing public transport companies to participate in the rapidly advancing development of battery technology. Behind the abbreviation NMC 3 is a new generation of high-performance batteries. An outstanding advantage is their enormous capacity, which enables a long range without opportunity charging. In addition, there is the modular design of the battery equipment. As before, Akasol is the partner for the production of the batteries.

The new generation are also lithium-ion batteries that are precisely formulated around cells with a new high-energy NMC cathode (NMC: lithium nickel manganese cobalt oxide), a liquid electrolyte and an advanced graphite anode. The common abbreviation NMC (nickel, manganese, cobalt) also stems from battery chemistry. Instead of the previous prismatic battery cells that are the size and shape of a paperback book, ultra-compact cylindrical cells with high-energy cell chemistry are used. Improved cell chemistry combined with an optimized battery pack result in an increase in the overall gravimetric and volumetric energy density of the battery pack. The capacity of 4.93 Ah per battery cell leads to a considerable increase in capacity of around 50 percent for the same weight.

600 battery cells are mounted within each battery module. They are integrated into the cooling circuit to ensure the battery’s optimum operating temperature of around 25 degrees Celsius. Temperature control ensures maximum service life and efficient charging. Nine battery modules combine to form a battery pack with 5400 cells. This results in a nominal energy of 98 kWh per battery pack.

Long range, individual battery equipment, enormous increase in capacity

As was customary from the start with the eCitaro, different battery equipment versions are possible for both the solo bus and the eCitaro G articulated bus. This means that even with the new battery generation, every public transport company will receive an eCitaro customized according to its individual usage profile.

The eCitaro solo bus can be supplied with at least four and no more than six battery packs with a combined capacity of up to 588 kWh. These are divided into three or four packs on the roof and two packs in what used to be the engine compartment. The eCitaro articulated bus has a minimum of four and a maximum of seven battery packs with a combined capacity of up to 686 kWh. Up to five packs are housed on the front section and, depending on the configuration, one on the rear section as well as in what used to be the engine compartment.

In average conditions, the top spec equipment ensures a reliable range of 280 kilometers for the eCitaro solo bus and 220 kilometers for the eCitaro G throughout the entire service life of the battery. This means that the buses cover the majority of the requirements of the daily driving performance of city buses. Under favorable conditions, the range is more than 300 kilometers.

The distribution of the battery packs results in well thought-out weight distribution down to the last detail. It ensures an appropriate number of passenger seats even with a large number of batteries. Added to this is the weight advantage from the high energy density of the new batteries: Depending on the vehicle configuration, the eCitaro with the new generation of batteries offers a considerably greater range for the same weight, and thus the same number of passenger seats.

Priority: Depot socket charging, optional opportunity charging

Thanks to its high energy capacity, the eCitaro with new generation batteries is also ideally suited for long routes and subsequent socket charging at the depot. This makes a charging capacity of up to 150 kW possible. The familiar positions are available on the left and right above the front axle and at the rear (a maximum of two positions per vehicle is possible).

If even longer routes are planned, intermediate charging via pantograph or charging rails is also possible, also referred to as opportunity charging in the technical jargon. In combination with charging rails, even the maximum configuration with batteries is attainable. In this case, the charging capacity goes up to 300 kW.

In addition to their high energy density, the batteries also have other advantages: The new generation already meets the safety requirements according to ECE-R 100-3, which will only become binding in autumn 2023. This specification includes a large number of tests and inspections. Durability with gentle depot charging is also impressive: Akasol as the manufacturer assumes 4,000 charging cycles, depending on factors including the depth of discharge and usage profile. With daily use and subsequent charging at the depot, this would correspond to a service life of up to ten years.

Innovative thermal management drastically reduces energy consumption

The battery capacity alone does not say enough about the performance and range of an all-electric city bus – the true benchmark is energy consumption.

In a city bus, energy consumption is strongly affected by the climatic conditions and thus by the cooling and, above all, the heating of the vehicle interior. Mercedes-Benz therefore places great emphasis on thermal management. Compared to the current Citaro with a combustion engine, the energy requirement for heating, ventilation and climate control is reduced by around 40 percent. This extraordinary energy efficiency lays the foundation for achieving a viable driving range for the eCitaro even under unfavorable conditions.

First, the NMC batteries are temperature-controlled to an ideal temperature of 25 degrees Celsius. This results in maximum charging capacity, performance and service life. The passenger compartment is heated in an energy-saving manner by a heat pump and, if necessary – in the event of significant temperature changes – supported by the braking resistor. The passenger compartment is connected to the water circuit in all models. The front heater is equipped with a double heat exchanger. The heat-dissipating components are interconnected to minimize the energy required to cool them. The performance of the heating and air conditioning system varies depending on the vehicle load and the outside temperature.

The roof-mounted air conditioning system is fitted with an additional heat pump function as standard. As a result, it heats the passenger compartment very efficiently, even at low outside temperatures. CO₂ is used as a highly efficient and environmentally-friendly refrigerant.

Another benefit is that the vehicle interior can be preconditioned to the required temperature while the batteries are being charged at the depot. This means that the energy for the required climate control is not drawn from the battery at the start of the trip and the range is increased. Even overconditioning is possible: In winter, the city bus then starts from the depot with a higher temperature in the passenger compartment in order to counteract the cooling from the outside, which further reduces consumption during operation. Similarly, precooling is somewhat stronger in the summer. Another advantage is that with an electrical climate system, the required output is always available. Conventional air conditioning systems, on the other hand, depend on the current speed of the combustion engine and therefore require greater output.

Proven, powerful portal axle

The drive of the new eCitaro is based on the proven and optimized ZF AVE 130 portal axle with electric motors on the wheel hubs. The peak power of the motors is 2 x 125 kW and the torque is 2 x 485 Nm. Thanks to the gear ratio, a torque of 2 x 11,000 Nm on the axle is fully available from the start thanks to the system and ensures appropriate dynamics even with full occupancy. In the case of articulated buses, the center and rear axles are powered as standard.

Cockpit and operating concept correspond to the conventionally powered Citaro

The layout of the eCitaro's passenger area corresponds to that of the usual Citaro models. The driver of the eCitaro does not have to get used to anything new, just like the passengers. The cockpit and operating concept of the city bus largely correspond to the usual setup unchanged. The direction of travel is selected as usual with the D N R pushbuttons.
The almost identical operation compared with the Citaro featuring combustion engine therefore enables the usual quick change of driver.

However, the instrumentation meets the requirements of the electric drive: Here, a power availability display replaces the tachometer. It shows the current power demand or recuperation. The driver also receives information about the state of charge of the batteries. From the central display, the driver can access the range, power availability and a charging indicator.

The eCitaro also supports the driver in energy-saving driving with acceleration control: When moving off from a bus stop or traffic lights, whether empty or under full load, the torque is reduced to a comfortable level. This leads to a gentle, passenger-friendly driving style and at the same time reduces energy consumption.

In general, the driving properties are optimized for maximum efficiency without the driver having to observe major differences from the Citaro with a combustion engine. For example, the basic setting of the bus is energy-efficient when the driver takes his foot off the accelerator pedal and coasts. Alternatively, the driver can set a basic deceleration – similar to the engine drag torque or the retarder effect from the diesel bus – as a recuperation rate using an e-brake lever in several stages.

The unrivaled safety of the eCitaro

Safety does not consist of individual measures for Mercedes-Benz buses; behind it is a comprehensive, integrated safety concept. With the eCitaro, this begins with the driver-fitness safety. Its cockpit corresponds almost completely to the usual cockpit of the Citaro and does not require any getting used to. The seat, visibility, ergonomics and climate control are exemplary. The comfortable and secure suspension with electrohydraulic intelligent eco steering and anti-roll/pitch control has earned major recognition.

A safety focus includes high-voltage technology with impact-proof mounted battery modules and well-protected high-voltage cables. The batteries are tested and certified according to hazardous goods regulations. Tests of the cell, cell module, battery pack and the battery groups in the vehicle have shown that the battery systems are extremely safe.

The active safety of the eCitaro is unmatched. The solo bus is fitted with the ESP electronic stability program and its numerous sub-functions. Mercedes-Benz optionally supplies the eCitaro with the Sideguard Assist cornering assistant with pedestrian detection and with Preventive Brake Assist, the first active brake assistant for city buses.

E-mobility system: Comprehensive advice and service when switching to electromobility

E-mobility requires specific services that keep pace with developments on the vehicle side. For this reason, the Omniplus service brand from Daimler Buses has converted its range of tailor-made eService contracts to a modular concept with the introduction of the new battery technologies.

In addition, the well-known eBasic and ePremium service contracts are still optionally available to public transport companies. They offer package solutions for repair and maintenance work on the high-voltage components as well as on the overall vehicle. The optimum service for the electric bus fleet can thus be put together from the basic warranty, extended battery warranty and service contract modules in a customer-specific manner and in accordance with requirements.

As if that were not enough, the Omniplus TrainingCenters in Dortmund, Mannheim and Winterthur/Switzerland provide information on the equipment of an e-bus workshop on request and offer a complete training concept for e-mobility for employees in driving operation or those employed in a workshop.

In a public transport company, the switch to electromobility is about more than energy consumption and range. Mercedes-Benz uses plug-in charging in the depot as standard. Opportunity charging is also possible on request, either by pantograph, which means current collector on the roof, or by combining charging rails and fixed current collectors. The experts at Mercedes-Benz have tested various charging infrastructures. They will provide advice and make recommendations. And the eCitaro can also be delivered as a complete package with power supply equipment on request.

The power supply of the buses is the heart of e-mobility in a city center. Mercedes-Benz eMobility Consulting will provide support in the planning of infrastructure, calculate the necessary power supply, know the routes to distribution network operators and power suppliers and recommend the appropriate charging technology – right up to the organization of the depot with parking spaces and the power supply to the bus including its battery equipment.

The eCitaro is communicative and connects to the charging infrastructure with ISO 15118 protocol. Mercedes-Benz offers solutions for integrating vehicle-specific data into existing management systems. Companies will be able to gain an insight into the operating data of their fleet using the Omniplus On Portal. Mercedes-Benz offers integrated system solutions for maximum transparency from block scheduling to depot management together with the industry-renowned ITS software provider IVU Traffic Technologies.