As with other inductive charging systems, this new development from BMW and Daimler sees vehicles parking above a conductive charging mat with an electronic coil, which is able to transfer energy to an on-board coil to recharge the EV’s battery wirelessly.
BMW believes the use of coils will enable the charging tech to be lightweight and compact, while concentrating the magnetic field for an ‘efficiency-factor’ of over 90 percent.
Initially the charging mat will charge the car’s battery at a rate of 3.6kW, which sees a charging time for many EVs of less than three hours, however BMW has charged one of its own i8 sports cars in under two hours using a prototype charger.
BMW believes the charging rate could be almost doubled to 7.0 kW in the future, which would result in even faster charging times or facilitate batteries with a higher energy capacity.
As the driver approaches the charging mat, a WiFi connection between mat and vehicle helps the driver guide the car to the ideal stopping point for maximum efficiency. The driver can then get updates on the car’s charge-rate via a mobile phone.
BMW says rain and snow will not affect the system, which can be safely used outdoors, and the system will halt charging if a ‘foreign body’ is detected around the charging coil.
The inductive charging system from Daimler and BMW adds to BMW’s recent solar charging carport concept as a means of future EV ‘refuelling’, while Volvo and perhaps Nissan are also keen on developing wireless charging technology.
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