Electric truck for the city.
Distribution transport or the famous last mile to the customer is one of the major challenges for future logistics. The more attractive the metro areas become – some 70 percent of what will then be nine billion people will live in cities by the year 2050 – the higher the requirements on an environmentally friendly provision of the population. The residents of the megacities want to be supplied with goods and services without accepting any sacrifices to their quality of life due to traffic. This poses new challenges to the logistics industry. With the newly presented Mercedes-Benz Urban eTruck, the world market leader for commercial vehicles addresses this development: locally emission-free supply from the warehouse into the city is becoming reality.
Commercial vehicle applications now makes economic sense
In the past, the potential uses of electric trucks were very limited. But in the meantime the costs and also the weight of the electric powertrain have dropped far enough to make profitable use in commercial vehicle possible. In future, locally emission-free trucks will distribute the goods in cities from sites on the outskirts. Currently, the Fuso Canter E-Cell is already demonstrating the merits of an all-electric powertrain in a light-duty distribution truck (up to six tonnes) in a field test in and around Stuttgart.
All-electric truck for heavy-duty distribution transport
The Urban eTruck brings the battery-electric powertrain even to a truck with a gross vehicle weight of 26 tonnes. The electric truck benefits from a rapid trend reversal because battery power, operating range and charging times have all continued to evolve steadily in recent years. The energy storage units in the Urban eTruck come from Daimler subsidiary Deutsche ACCUmotive. When the truck hits the market in a few years, it will have an operating range of 200 kilometres – enough to meet the day-to-day requirements in distribution transport. In addition, Daimler Trucks expects the battery costs to drop from 500 euros per kilowatt hour to 200 euros per kilowatt hour by the year 2025.
The three-axle truck is powered by electric motors installed right next to the wheel hubs on one rear axle. The axle is based on the ZF AVE 130 model, which has already proven its mettle as a low-floor portal axle in the hybrid and fuel-cell buses from Mercedes-Benz. (see sidebar)
In future, locally emission-free trucks will distribute the goods in the cities.
Full power from the start
However, the axle was revised for use in the Urban eTruck to achieve a ground clearance of more than 200 mm. The developers opted for a liquid-cooled asynchronous three-phase motor on each side to power the vehicle. The supply voltage is 400 V with a peak power of two times 125 kW. Drivers will be captivated by the peak torque of two times 500 Nm, which as with all electric motors is available from start. With regard to performance, the electric truck is on par with a conventional diesel truck.
A battery pack with three modules
Thanks to the modular design of the energy storage unit, the battery capacity of the Urban eTruck can be tailored to the different requirements. The basis is a battery pack with three modules of lithium-ion batteries and a capacity of 212 kWh, which translates into an operating range of 200 kilometres.
However, power and operating range can be adapted to the individual mission profiles like a conventionally powered truck. An intelligent battery management system, likewise developed by Deutsche ACCUmotive, optimises the balance between service life and performance of the electric urban truck. The batteries are recharged at permanently installed charging stations with a charging capacity of up to 150 kW. Totally empty batteries can currently be recharged fully in two to three hours.
In addition, the electric operating range also benefits from converting braking power into electric energy. Every time the truck decelerates, the electric motors mutate into generators that convert braking energy into electricity and in this way recharge the batteries. Apart from recovering energy, this also reduces wear and tear on the brakes, which lowers the maintenance costs for the trucking company.
Every time the truck decelerates, the electric motors mutate into generators.
The time is ripe for the electric powertrain
The electric powertrain of the urban electric truck represents an added weight of about 1.7 tonnes. However, because the EU Commission approves uprating the gross vehicle weight of trucks with alternative powertrains by up to one tonne, the additional kilos are virtually compensated for.
No question, the time is ripe for the electric powertrain in commercial vehicles as well. Among the light-duty trucks the Fuso Canter E-Cell will now be followed by the 26-tonne Urban eTruck at the start of the next decade. And in two years, the first electric bus is slated to hit the roads, meaning that electrically powered and locally emission-free vehicles will then be able to meet all urban logistics requirements.
Empty batteries can currently be recharged fully in two to three hours.
Compact and efficient powertrain.
As the basis for the Urban eTruck, the Daimler developers used the AVE 130 portal axle system with two electric motors integrated near the wheels directly into the wheel ends, which thus far has been used in buses. This axle system is versatile enough to be used for all conceivable sources of electric energy. The vehicle is powered by compact asynchronous motors, which unlike permanently excited synchronous motors do not use rare earths. Compared with a conventional solution with one central electric motor, the compact design weighs up to 500 kilograms less. A patented cooling system lowers the temperature of the powertrain units and disperses heat more evenly to boot. As a field test in a bus proved, this resulted in significantly lower energy requirements than with a comparable diesel engine. The powertrain also betters conventional powertrains in terms of comfort, because the acceleration from rest to top speed is not interrupted by gear changes.