E-mobility: charging at the depot

Companies wishing to add electric trucks or buses to their fleet often play around with the idea of charging the vehicles at their depot. Jan Wohlmuther, who is responsible for eConsulting at Mercedes-Benz Trucks, and his team assist customers in setting up the charging infrastructure they require. “We sit down together with the customer to first develop an application concept. Then we produce a usage profile based on the customer’s routes and shift scheduling to ensure that the charging infrastructure matches the routes,” reports Wohlmuther. Companies that can charge overnight at the depot do not require an expensive 160 kW charging station for each truck – a 50 kW charging output would suffice in this case.

Rainer Schmitt, Managing Director of Logistik Schmitt, a logistics company based in the German town of Bietigheim, also sat down with the Daimler experts. The freight forwarding company has been testing a prototype of the Mercedes-Benz eActros since 2019. The company currently uses an 80 kW output mobile charger unit. “Mobile units are a great solution for testing purposes, but their output is limited. It is also more convenient to use a charging station,” continues Wohlmuther. Soon Schmitt will take delivery of a new second-generation eActros and the vehicle be put through its paces: “It will have to cover 300 kilometers a day in a three-shift operation, and we will have to charge it just as quickly,” explains Schmitt, adding: “To achieve this, we initially drew up a timetable, and defined the route on which the truck is to be used, how many kilometers a day it will drive and how long the charging stops can be.” A 160 kW output charging station is now being installed at the company’s depot in Bietigheim. There is already a transformer box with the appropriate capacity at the freight forwarding company’s site and so the cable routes are correspondingly short.

Wohlmuther advises customers who are just starting to consider: “The better the planning and the more thought they give to this in advance, the better and more competitive the entire charging infrastructure will be.” Complexity and cost are not proportional to each other – half the output is not half as expensive. And it will be twice as expensive if the depot has to be excavated again in three years’ time due to poor planning. It is crucial to factor in reserves, but oversizing the infrastructure also leads to unnecessary costs. It is therefore worth considering the company’s business model for the next five or ten years: Will the company win new customers, operate new routes, how good is the financial position?

Once the planning phase has been completed, it is now time to bring the network operator on board. If the customer wishes them to, the eConsulting team at Mercedes-Benz Trucks, which works with Siemens Smart Infrastructure and local installation partners in the German-speaking region, can organize this. “The network operator checks the situation on site and, if necessary, extends the network connection. These requests are generally met within the scope of the statutory supply obligations. The costs are allocated to the orderer by the building cost subsidy,” explains Wohlmuther.

We are generally talking about a low-voltage connection with a total output of less than 250 kVA (approximately 200 kW). The associated transformer box is then usually located on the road. From there, the cables are routed to the building connection and to the charging stations. “When cables are routed within your own depot, you can to make sure that the conduits are sized slightly larger. That way, another cable can be pulled in later,” says Wohlmuther. A medium-voltage connection with its own transformer is usually required with outputs of over 250 kVA, say with two charging stations each producing 160 kW of power. With a suitable infrastructure, ideally it will take around four months from initial planning to commissioning. It can take up to 18 months if major reconstruction work needs to be undertaken by the network operator.

Depending on the situation on site, the Head of Mercedes-Benz Trucks eConsulting estimates that it will cost around €250,000 for the construction of the infrastructure, including a new transformer and cables from the medium-voltage ring main for five charging stations, each producing 160 kW. The charging stations cost extra: €60,000 to €100,000 for a 150 kW fast-charger, depending on the model and equipment. A 50 kW charging output is cheaper with a charging station then coming in at around €20,000 to €40,000. The German Federal Ministry of Transport and Digital Infrastructure (BMVI) bears up to 80 percent of the cost of the planning and construction of the charging infrastructure. Most operators regard it as a long-term investment in the future in any case. “In our experience, this expenditure is expected, but companies are nonetheless happy to take advantage of the funding,” states the expert Wohlmuther.

The logistics service provider Contargo relies on electric mobility and wishes to continue investing. In 2019, the Duisburg company purchased two electric trucks and charges them on the road. In 2020, Contargo then installed a 150 kW fast-charging station in Neuss. The charging station uses green electricity. “We want to expand our fleet of electric trucks and plan to install a further 15 charging stations,” reports Kristin Kahl who is responsible for sustainability at Contargo. Thanks to their charging capacity of up to 250 kW, the batteries are quickly recharged while the truck takes a quick 15-minute break. It is advisable to factor in buffer storage capacity to deal with peak loads. “This kind of storage is currently only affordable with funding, but it prevents our operating costs from rising,” continues Kahl.