The Mercedes-Benz S550e is getting a face-lift for 2017, and with it comes the wireless charging system we heard about when the plug-in hybrid first hit the market. The option will be the first commercial application of a Wireless Electric Vehicle Charging (WEVC) system on a hybrid.
The S550e's available WEVC system will be supplied by a Tier 1 power electronics company that has licensed Qualcomm Halo technology. Qualcomm says its Halo tech was tested and further developed by the BMW i8 Formula E safety car. Just like the safety car, S550e hybrids equipped with the wireless charging option can park over a special charging pad to begin juicing up. Halo uses resonant magnetic induction to transmit energy, a process that's comparable to conductive charging's 90-percent efficiency rating, according to Qualcom. The company also says Halo's efficiency improves as power increases. Currently, the system runs at 3.6 kW, which is fine for a plug-in hybrid with a small battery like the S550e and its 8.7-kilowatt-hour lithium-ion unit.
We spoke with Anthony Thomson, Qualcomm's vice president of business development and marketing, for more details on the system and the company's future wireless charging plans. The Halo system uses a pad with multiple coils that transfers energy via a dense magnetic field to a laptop-sized receiving pad on the bottom of the vehicle. Up to 800 volts is available for performance applications, but most of the time voltage is stepped down to 400 volts. Thomson says the commercial system has a max rate of 11 kW, but Qualcomm has achieved as high as 125 kW charging big buses in the U.K. However, the company sees frequent charging at lower speeds as the best application of the technology, with cars "snacking on energy" at every stop on their daily route. This would negate the need for 150-kW fast chargers like Tesla's Supercharger network.
Eventually, Thomson says the technology can be adapted for roadways so EVs can charge on the go. Qualcomm is working on an in-road inductive charging system to demonstrate the feasibility of a future highway charging infrastructure. Such a system could roll out first in ultra-urban areas. For this to work best, future cars would have smaller batteries, making them lighter and requiring less energy to go and stop.
Because the magnetic field can heat things up like a microwave, the cars of tomorrow would have object detection to sense when an animal or debris is about to enter the field. Halo can transmit full power over 250 mm (nearly 10 inches), enough to reach SUVs with reasonably good ground clearance. The system can tolerate a 150x150-mm misalignment of the pad and receiver. Some buses can lower to create an ideal gap, but the efficiency gains aren't worth the added cost and risks, according to Thomson.
Expect to see wireless charging on the options list when the refreshed 2017 Mercedes-Benz S550e arrives next year.
Frank Markus contributed to this post.