Charging Without Wires

For drivers of electric vehicles, replenishing their battery when they’re not at home is still a cumbersome process to say the least. If and when a charging station is available, the required cables can be hazardous to pedestrian traffic by adding to street clutter, and they’re easily stolen for their copper content. Wireless charging through electrical induction has been considered as an alternative, but is too expensive to be a practical solution. Now, several companies are looking at bringing induction charging technology to the masses at a cost that is comparable to wired charging systems.

The first step was to create a pad to amplify the magnetic fields generated that can be easily buried in the ground. The vehicle must then be equipped with a suitable pickup coil so that, when parked above the pad, a similar current is induced in the pickup, ultimately charging the battery. Although power losses through the air gap average about 11 percent, wired chargers exhibit comparable losses by requiring special transformers to protect against power surges.

A vehicle can be retrofitted with the required pickup circuitry for between $2,500 and $4,000, although this is an after-market modification that may affect warranties. The developers are currently working with vehicle manufacturers — including cars, buses and freight movers — to install the technology at the factory.