New Electric Bus Charges Through Its Tires With Over 90 Percent Efficiency

Published Oct 12, 2026

An electric bus in Switzerland now charges through its tires, and almost none of the power goes to waste. Winduction, a spin off from ETH Zurich, built the new electric bus tire charging system. It moves energy from the road straight into the battery at over 90 percent efficiency. This idea is simple and clever. After all, the wheel is the only part of a vehicle that always touches the ground. So Winduction put the receiving coils inside the tire itself.

First, coils set into a plate in the road connect to the power grid and create a magnetic field. When the bus stops over the plate, coils inside the tire pick up the energy. The power then flows into the vehicle battery. Inductive charging is not new. Phones charge on small desk plates, while some electric cars already charge without cables. Yet those systems aim at the underside of the vehicle, where the gap is large and changes with each model.

This gap is the whole problem. In fact, energy transfer gets weaker as the distance grows. So conventional wireless chargers lose a lot of power between the road and the chassis. ‘We minimize the large transmission distance between the road and undercarriage by placing coils inside the wheel,’ said ETH alumnus Sylvain Fricker, who leads technology at the company. Meanwhile, the name Winduction itself stands for wheel based induction, the idea behind tire charging for an electric bus.

From the ground into the vehicle, the electric bus tire charging system keeps over 90 percent of the power. In contrast, less than 10 percent is lost along the way. This makes it nearly as good as plugging in a cable. Steel, however, was the big hurdle. Normal bus tires contain steel belts for strength. But steel reacts with the magnetic field and turns much of the power into heat instead of passing it on.

So Winduction is developing a completely new steel free tire with partners. It uses composite materials instead of steel for reinforcement. Still, the extra cost per tire is tiny next to the cost of running a whole bus line. Interesting Engineering reports the electric bus tire charging setup can deliver up to 40 kilowatts per wheel at each stop. Buses charge while passengers hop on and off. About three hours of top ups across a 16 hour day can replace five hours of overnight depot charging.

Smaller batteries change everything. Buses then become lighter and cheaper to buy and run. They also free up room for more passengers, since huge battery packs no longer eat up space. Sonam Bhuka, Sylvain Fricker and Laurin Schwitter founded the startup. Schwitter serves as chief executive. Fricker added that short charging stops let buses run on much smaller batteries, which makes them significantly cheaper to buy and operate.

Winduction tested the math for charging through the wheels on a real bus line between Zurich Airport and the Oerlikon quarter. The route has 24 stops, yet only two would need charging plates. This is all it takes to keep the buses running all day. According to Winduction’s calculations, total costs over the life of a bus line could fall sharply. How large the savings are depends on the route. A feasibility study with transport operators is now putting numbers on it.

Daytime charging brings another win for electric bus tire charging. Electricity also keeps getting cheaper during the day as solar power grows across Switzerland. It also avoids the heavy load of charging every bus at the same time overnight. Other teams are chasing similar dreams. Engineers are testing charging while driving on real roads. Finnish scientists even sent electricity through air using sound.

Winterthur is where the company is now building test infrastructure, with support from the Federal Office of Transport and the Swiss Climate Foundation. It includes a test lab and also the company’s own test bus stop for trying the charging setup. The first pilot with real passengers is planned for 2028 around Zurich Airport. Talks with Swiss transport operators, meanwhile, are already underway. Passengers will notice nothing, since the ground plate transfers power quietly and without wires.

This is the kind of idea that feels obvious only after someone builds it. Buses already stop all day long, so the charging happens inside time that was wasted anyway. If the 2028 pilot works, electric bus tire charging could spread to cities everywhere. Its future may be hiding in the humblest part of the bus. That tire was always touching the road. Now it is drinking from it too.

Source:Switzerland Tests Electric Bus That Charges Through Tires