A sophisticated charging strategy enables Vikingbus, based in Køge, Denmark, to make extremely long round trips in their eCitaro buses.

A medieval marketplace, ancient half-timbered houses and a 16th-century castle: the town of Køge, 30 kilometres south-west of the Danish capital Copenhagen, has a long history and currently around 35,000 inhabitants. It is also moving towards the future in leaps and bounds. Not only has the entire city bus service recently gone fully electric and locally emission-free, the town is also home to Denmark’s currently longest electric bus route, which is almost 50 kilometres long. The eCitaros used on this circuit have to cover ranges of 500 kilometres per day.

Vikingbus, a consortium of 17 Danish companies, is one of the largest bus operators in Denmark and operates regular services in six Danish cities, including Køge. In Køge, the company recently switched its entire scheduled-service bus fleet from diesel to electric buses. At the turn of the year 2023/2024, 31 Mercedes-Benz eCitaro buses joined their team. “Our fleet of more than 450 scheduled-service buses and touring coaches throughout Denmark consists mainly of vehicles from Daimler Buses”, says Brian Thrige, project manager and buyer at Vikingbus. "We appreciate the high quality and reliability of the buses and the good customer service. That’s why we also opted for the eCitaro when switching to electromobility in Køge." The 31 solo buses serve nine routes every day in the Køge town area and the immediate vicinity in the eastern part of the island of Zealand.

The buses run from five in the morning until one in the morning during the week and sometimes even around the clock at weekends. The long daily operating times and the enormous mileage travelled per day initially posed logistical challenges for bus operator Vikingbus when switching to electric buses. Even for an eCitaro with a maximum battery capacity of 588 kWh, round-trip times of up to 20 hours per day and ranges of 500 kilometres without recharging are no easy task.

Nevertheless, Vikingbus decided against opportunity charging with pantographs and in favour of plug charging at the depot. The solution: split shifts. The buses start work at staggered intervals in the morning and return to the depot for charging after nine o'clock once the first rush hour has died down. During this time, other fully charged eCitaro buses will take over scheduled services. Thanks to a charging capacity of 150 kW, in just a few hours the batteries are full enough again to take over the afternoon shift and keep going until after midnight.

Vikingbus also uses this charging strategy on Denmark’s longest electric bus route to date between Køge and Stevns, which is located around 25 kilometres further south. To reliably cover daily ranges of 500 kilometres and more even in winter with interior heating or in summer with the air conditioning switched on, Vikingbus has installed an additional charging station at the far end of the line. This means that the eCitaro buses used on this line can recharge during scheduled breaks.

“This charging strategy has proven successful in practice.” Project manager Brian Thrige summarises their experiences over the first few months. "The eCitaro runs absolutely smoothly. And with the battery capacity of 588 kWh and interim charging in the depot, we can easily serve even the most demanding round trips in Køge." Thrige is confident that the example of Køge will set a precedent within Vikingbus and that more eCitaro buses will soon start operating in other Danish cities.