The charging time depends essentially on the vehicle’s charging type and battery size. Charging in the depot is currently 150 kW, while pantograph charging can be up to 450 kW. For a battery with 400 kWh, the charging time is about 6 hours for depot charging and 2 hours for pantograph charging.

A battery bus, also called an electric bus, e-bus or accumulator bus, is a bus that is powered by an electric motor and, in the same way as an electric car, draws its propulsion energy during the journey exclusively from a traction battery carried on board.

A total of 727 buses with electric engines were registered in Germany at the beginning of 2021 (source: de.statista.com).

VDV 463 is an interface that regulates communication between the charging management system and the upstream systems of the transport companies (traffic control system (ITCS) and depot management system (BMS)). This means that planning requirements from operations are taken into account when controlling charging processes via the charging management system, and important vehicle status data is also transferred to the upstream systems.

VDV 261 defines how the charging management system communicates with the vehicle via the charging station with regard to preconditioning. It is based on an extension of ISO 15118.

Buses can be charged conductively (physically connected to charging station) with direct current or inductively (contactless) with alternating current. Charging begins fully automatically once the vehicle and the charging station have been connected and data has been exchanged between the two systems. In addition to overnight charging at the depot, there are also concepts in which the vehicles are briefly charged at high power at each end of the line. Different charging concepts will make more sense, depending on the line length and route profile, for example, one option could also be inductive charging at individual stops.

The larger the fleet, the more important charge management is. Controlling and monitoring multiple charging processes is very time-consuming and can lead to problems without charge management. For example, power connections can be overloaded or vehicles might not be fully charged in time, which could lead to outages.

Charging can be monitored using central charging management software. The charging management software exchanges information with the vehicle, gives commands to the vehicle, and graphically displays the current information status . Charging management software can also exchange data with other systems and use information from other systems to integrate the status information into the user’s context. The software is location-independent and can be used from anywhere.

The charging processes can be controlled in different ways. Technically, the charging station controls the charging process in close cooperation with the vehicle. Basically, the vehicle communicates how much energy it needs and the charging station supplies the energy according to a prescribed charging profile. The charging profile can be improved by charging management software.