The new NMC4 battery in the Mercedes-Benz eCitaro: More capacity, longer service life

• Proven large-scale production technology
• Higher power density, longer range
• Long service life despite fast charging
• More safety thanks to monitoring even when idling
• Sustainable lifecycle management for NMC batteries

At the UITP Summit 2025 in Hamburg from 15 to 18 June 2025, Daimler Buses will be presenting a Mercedes-Benz eCitaro with the latest NMC4 battery generation to the public for the first time. The fourth generation of lithium-nickel-manganese-cobalt batteries – the successor to the current NMC3 technology – combines a high energy density, which facilitates longer ranges in electric buses, and a very long service life. The new NMC4 batteries will be used in the Mercedes-Benz eCitaro, eCitaro G and eCitaro K low-floor city buses from 2026.

Proven large-scale production technology

The NMC4 battery represents proven technology from the battery system expert BMZ Poland, a company belonging to BMZ Holding. This technology has already been manufactured in large-scale production for other applications since 2022, and BMZ has worked together with Daimler Buses to enhance it for use in buses. Unlike NMC3 batteries, the individual cells of the NMC4 battery are not cylindrical, but prism-shaped. Twelve cells make up each module, and 15 modules form a battery pack. The design of the NMC4 battery packs corresponds to that of the NMC3 battery model currently in use. The new battery generation is therefore compatible with the current eCitaro in series production without any modifications to the vehicle. If all battery packs in an existing eCitaro vehicle ever need to be replaced, even retrofitting is conceivable thanks to the compatibility between the NMC generations.

Higher power density, longer range

Due to a change in the composition of the cell chemistry, the energy density in the NMC4 battery is nearly six percent higher compared with the NMC3 battery, thus ensuring higher storage capacity with the same installation space. While a fully charged NMC3 battery pack contains 98 kWh of energy, the NMC4 battery has 111 kWh of energy. In addition, a higher proportion of the stored energy can actually be used for driving. Consequently, the possible ranges that can be achieved without recharging are also significantly increased.

Long service life despite fast charging

Another important benefit for customers is the longer service life of the NMC4 battery and the resulting longer mileage of the eCitaro. Fewer battery replacements and less need for recycling contribute to sustainability and a reduction in the total cost of ownership (TCO) of the eCitaro.

The longer service life of the battery is achieved in part thanks to gentle, slow charging with a maximum charging capacity of 150 kW. However, the cell chemistry of the new battery is particularly beneficial during regular rapid charging processes with up to 300 kW charging capacity and can also impress with an extended service life in these applications. Daimler Buses is taking this opportunity to guarantee a service life of eight years for the new NMC4 batteries and to offer an optional extended warranty with a term of twelve years.

More safety thanks to monitoring even when idling

The new battery generation can also impress in terms of safety. For example, battery monitoring in the NMC4 battery, i.e. thermal monitoring and alarms in the event of overheating, not only works when the operating system is switched on, as in previous vehicles, but also when the vehicle is idling.

Omniplus as a reliable partner throughout the entire lifecycle

Daimler Buses pursues a circular and sustainable approach to battery lifecycle management and offers suitable solutions for respective customer requirements via the Omniplus service brand. The modular concept allows the batteries to be repaired and overhauled during their first service life. Subsequent use of the batteries outside their first purpose in the vehicle extends their service life by a second service life in an energy storage system. At the end of the entire service life, the high-voltage batteries are recycled with the aim of recovering raw materials.

Long range, individual battery equipment, vast increase in capacity

As usual, different versions of the battery equipment are possible for the eCitaro equipped with NMC4 batteries from 2026, both for the solo bus and the short eCitaro K as well as for the eCitaro G articulated bus. The battery packs of the new NMC4 battery generation have the same dimensions as the NMC3 packs. As before, the eCitaro solo bus and the short eCitaro K are therefore available with at least four and a maximum of six battery packs, which now have a combined higher capacity of up to 666 kWh. The high-voltage batteries are divided into three or four packs on the roof and two packs in the former engine compartment. An exception is the version with four batteries. Here there are three on the roof and only one in the compartment.

The eCitaro G articulated bus is equipped with a minimum of four, and a maximum of seven battery packs and a total capacity of up to 777 kWh. Depending on the configuration, up to five packs are located here on the front section and one each on the rear section and in the former engine compartment.

The maximum equipment scope guarantees a reliable range of up to 500 kilometres for the eCitaro solobus and eCitaro K and up to 400 kilometres¹ for the eCitaro G. This means that the buses cover the majority of the requirements for the daily mileage of city buses.

Prioritised depot charging at the charging socket, optional opportunity charging

Thanks to its high energy capacity, the eCitaro with the new battery generation is also ideally suited for long cycles and subsequent charging at the charging socket in the depot. During this process, a charging capacity of up to 150 kW is possible. The familiar positions on the left and right above the front axle and at the rear are available for this purpose. An additional connector position is also available at the front of the vehicle. A maximum of two positions are possible per vehicle. Two eCitaro buses can also be charged sequentially, i.e. one after the other, at a charger with two charging points. This avoids charging peaks, saves infrastructure costs and still offers the operator the necessary operational flexibility.

For even longer routes, intermediate charging using a pantograph or charging rails is also possible – referred to as “opportunity charging”. The maximum configuration of batteries is even possible in combination with charging rails on the roof of the bus. In this case, the charging capacity is up to 300 kW. In addition, the charging rails can be optionally equipped with an RFID tag to ensure clear vehicle identification during charging at the depot.

Innovative thermal management drastically reduces energy consumption

The battery capacity alone does not provide enough information about the performance and range of a fully electric city bus – the true benchmark is the energy consumption. In the case of a city bus, this is very strongly influenced by the climatic conditions and thus by the cooling and, above all, heating of the interior. Thermal management is therefore given great consideration by Mercedes-Benz. For example, the high-voltage batteries are tempered to the ideal temperature. This results in maximum charging capacity, performance and service life. The passenger compartment is heated in an energy-saving way by a heat pump. If required – in the event of significant temperature changes, for example – this is supported by the braking resistor connected to the water circuit.

For maximum efficiency, the eCitaro has from the beginning been equipped with a state‑of-the-art CO2 air conditioning system with sophisticated thermal management, which is operated with the refrigerant R744. The EvoThermatik Basic air conditioning system is also available for the eCitaro for use in moderate temperatures, and the EvoThermatik High Comfort air conditioning system is offered as an additional option for use in hot countries. All air conditioning systems available for the eCitaro feature a highly efficient heat pump.

A further advantage: the interior can be preconditioned to the desired temperature while the batteries are being charged in the depot. This means that the energy required for climate control at the start of the journey is not drawn from the battery, thus increasing the range. Even overconditioning is possible: in winter, the city bus starts from the depot with a higher temperature in the passenger compartment in order to counteract cooling from the outside, which further reduces consumption during operation. Similarly, the system pre-cools the vehicle to a slightly lower temperature in the summer.

Proven electric portal axle

The drive system of the eCitaro is based on the proven and optimised ZF AxTrax AVE with electric motors on the wheel hubs. The motors’ peak output is 2 x 140 kW, while the torque is 2 x 495 Nm. Thanks to its ratio, it has an axle torque of 2 x 11 216 Nm, is fully available from the start thanks to the system and ensures adequate dynamics even when fully occupied.

Cockpit and operating concept identical to the conventionally powered Citaro

The layout of the eCitaro passenger compartment is identical to that in the Citaro. The almost identical controls compared with the Citaro with combustion engine therefore allows for ongoing quicker driver changes. However, the instrumentation meets the requirements of the electric drive, with a power meter replacing the rev counter. It indicates the current power requirement or recuperation. The driver also receives information about the charge level of the batteries. They can call up the range, power availability and a charge indicator via the central display.

The eCitaro also supports its driver in energy-saving driving with an acceleration control: when pulling away from the bus stop or traffic lights, whether empty or under full load, acceleration is reduced to a comfortable level. This leads to a gentle, passenger-friendly driving style whilst reducing energy consumption.

The eCitaro offers unrivalled safety

When it comes to Mercedes-Benz buses, safety does not consist of individual measures, but is based on a comprehensive integral safety concept. For the eCitaro, this starts with the driver-fitness safety. Its cockpit almost entirely corresponds to the familiar Citaro and requires no adjustment. Seat, visibility, ergonomics and climate control are exemplary. The comfortable and safe suspension, with the electrohydraulic steering system “intelligent eco steering” and roll and pitch control, has earned a lot of recognition.

A focus on safety includes high-voltage technology with crash-proof battery modules and well-protected high-voltage cables. The batteries are tested and certified in accordance with the hazardous goods regulations. The battery systems are very safe thanks to tests of the cell, cell module, battery pack and the battery groups in the vehicle.

The active safety of the eCitaro is unsurpassed. All models have a whole host of assistance systems as standard, including functions that, in some cases, go far beyond what is required by the General Safety Regulation (GSR) of the European Union.

For example, the second-generation, radar-based Sideguard Assist is standard equipment in the eCitaro. Sideguard Assist 2 reacts and provides even more accurate warnings if there is a risk of collision with pedestrians and cyclists. The system is now also used on the driver’s side. In addition, Sideguard Assist 2 assumes the role of a lane change assistant at speeds of over approx. 40 km/h. It notifies the driver about an object on either the driver’s side or the front passenger side up to the maximum speed. In critical situations when changing lanes, the system generates a visual and haptic warning. Sideguard Assist 2 thus supports lane changes, for example when overtaking a cyclist or when changing lanes/overtaking on multi-lane roads.

Frontguard Assist detects and warns of obstacles or people immediately in front of the vehicle. Together with the now standard reversing camera or, especially the optional 360° camera system (270° camera system for articulated bus variants), the driver is provided with a comprehensive information and warning system for all areas around their eCitaro bus.

The intelligent Traffic Sign Assist speed assistant warns when the permissible speed is exceeded. The Tyre Pressure Monitoring system (TPM), Attention Assist (AtAs) and an interface for the use of alcohol testers for the driver’s workplace have also been adopted as standard equipment on the eCitaro.

Daimler Buses Solutions: multi-faceted electromobility from a single source

Daimler Buses Solutions GmbH advises transport companies and actively supports them on their journey to electromobility. The company specialises in designing, building and advising on electromobility infrastructure. In cooperation with experts from Daimler Buses Solutions GmbH, Daimler Buses can supply the entire eMobility ecosystem from a single source on request: from the feasibility analysis to individually configured electric buses and the complete electromobility infrastructure – including construction measures, electrical installations, charging infrastructure including maintenance and service, battery storage, charging management systems and other digital services. A new feature in the portfolio is the Charging-as-a-Service offering, in which Daimler Buses takes over the operation of the charging infrastructure completely and the customer can conveniently charge at their own depot with monthly billing.

Omniplus: new digital services for electric buses

Another advantage for all eCitaro vehicles is the comprehensive service provided by the Omniplus service brand. This not only has the largest service network in Europe, but its network of specialist e-bus service centres with employees qualified to work on high-voltage components and the corresponding technical equipment already covers more than 110 eBus service centres in Europe and is growing all the time, too. In addition, digital services are becoming increasingly important as they offer users the opportunity to make bus operations even more efficient, economical and safe. With its Omniplus On Portal, Daimler Buses offers a wide range of digital services: from the Uptime and Uptime pro online remote diagnosis feature, to location services, consumption and driving analyses, through to Remote Charge Control for electric buses. With the current Digital Services Package, all buses delivered by Daimler Buses from this year onwards will temporarily receive many digital services as a free option. This service can be used for diesel buses free of charge for three years and electric buses for six years. Another new feature is the Omniplus On monitor tracking services plus service. This allows speed-based geofencing to be set up, which uses the vehicle’s position data to activate the speed limiter. The new service increases safety and takes the strain off drivers.

_{1 The range was determined internally under specific conditions, including equipment with maximum battery capacity, battery in as-delivered condition, in typical city bus operation and in a moderate weather scenario, and may, for example, deviate from the values determined in accordance with Regulation (EU) 2017/2400. The actual range depends on the individual use of the vehicle, the vehicle configuration and other external factors. For this reason, the actual range may be below or above the specified value.}