In-motion charging electric bus

In-motion charging (IMC) electric bus, also known as a battery trolleybus or trolleybus with extended autonomous run, is an electrically powered public transport vehicle that draws power from an overhead contact network (catenary) via trolley poles while simultaneously charging an on-board traction battery. This technology allows the vehicle to operate continuously: drawing power and charging while under the overhead wires, and operating as a battery electric bus on sections of the route lacking this infrastructure.

This concept is an evolution of the traditional trolleybus, developing from vehicles with small auxiliary power units for emergency use to modern systems where vehicles can cover significant distances autonomously, often between 15 to 70 kilometres (9.3 to 43.5 mi).

IMC systems are being actively implemented by major metropolises (e.g., Beijing, Saint Petersburg, Mexico City) and in transport networks across developed countries (e.g. Switzerland, Germany, The Netherlands). Modern In-Motion Charging systems can offer significant cost advantages over fully battery-electric bus networks.

Studies indicate that upgrading existing trolleybus infrastructure to IMC can reduce capital costs for rolling stock by approximately 50% and lower operational expenses by around 20% over a 15-year lifecycle compared to new battery-electric bus fleets. When building an IMC system from scratch with partial overhead lines, capital expenditures can still be lower than a fully battery-based system, due to reduced battery capacity requirements, a smaller fleet size and eliminated downtime during charging.