Daimler and BMW have agreed to jointly develop and implement a common technology for wireless charging.

The system consists of two components: a secondary coil integrated into the under tray of the car and a primary coil integrated into a floor plate that can be placed on a garage floor. Electrical energy is transmitted at a power rate of 3.6 kW and efficiency of 90%.

The arrangement of the coils, and consequently of the field pattern, is based on a design derived from their circular shape that allows a compact and lightweight construction, along with effective spatial confinement of the magnetic field, according to BMW.

Once the vehicle is positioned above the primary coil, the driver starts charging at the push of a button. The process can also be controlled from a smartphone.

The system transmits data via a WiFi connection to help the driver with parking. The space between the coils is monitored, and charging can be halted instantly if any foreign bodies are detected. Rain and snow have no effect on the power feed – all conductive components are protected, so the primary coil can be installed outdoors.

The technology standard foresees the future possibility of increasing the charging rate to 7 kW, which would allow the battery in the BMW i3 to be fully charged overnight.

BMW is testing a working prototype of the system with the i8, and Mercedes-Benz said it plans to begin fleet testing with the S 500 PHEV “soon.”

Source: BMW, Daimler, Green Car Congress