If you’re old enough, you’ll remember this—phones used to be plugged into the wall with a cord that connected to a TAE jack. Then came cordless phones, where you just had to drop them onto a charging base. And the rest pretty much speaks for itself: cell phones, Wi-Fi, you name it. These days, if there's a way to cut the cord in electronics, we go wireless.
So why not? MAHLE has tackled these technical challenges head-on and is moving toward providing the automotive industry with an inductive, contactless, standardized charging solution ready for mass production. At its core, the concept is similar to how you wirelessly charge your phone by placing it on a charging pad.
The key difference is that an electric vehicle has to be charged wirelessly across a gap, due to its ground clearance.
Here’s how it works: Whether it’s a low-slung sports car, a mid-size station wagon, or a high-riding SUV, the vehicle is positioned precisely over a charging pad embedded in the ground. A second charging pad is mounted on the vehicle’s underbody to enable energy transfer. Each pad contains a coil. The ground coil generates a magnetic field using an alternating current at a frequency of 85 kilohertz. This magnetic field induces a voltage in the receiver coil, and the vehicle’s battery is charged via the power electronics.
In standard vehicles, the vertical gap between the two components is typically between 14 and 21 centimeters. The system is highly resistant to environmental factors—it continues to work even if the ground pad is covered with leaves or snow.
To ensure highly efficient energy transfer, the two charging coils must be precisely aligned– ideally, perfectly overlapping. “This,” explains Christopher Lämmle, Head of the Charging Systems Project House at MAHLE, “was the key challenge we solved with the DIPS–our Differential Inductive Positioning System.” Typical parking assist systems in today’s vehicles can guide a car into a space with an accuracy of about five to fifteen centimeters. That’s fine for everyday parking, but not nearly accurate enough for inductive charging. “That’s why our DIPS is ten times more precise,” Lämmle adds. In other words, DIPS can position the vehicle with an accuracy of just one centimeter.
“With this level of precision, we’re achieving a transmission efficiency of 92% or more—on par with traditional cable-based charging,” says Christopher Lämmle. DIPS can be integrated into the increasingly widespread automated parking systems in production vehicles or will be available as an assistance system for the driver with navigation via the vehicle display. If systems function interoperably and across manufacturers, they can be scaled up to mass production and offered at attractive prices. This makes standardization a key issue, and MAHLE achieved a breakthrough in this area in summer 2024: The American standards institute SAE International, comparable to the International Organization for Standardization (ISO) / International Electrotechnical Commission (IEC), has selected the MAHLE system as the global standard solution for wireless charging.
"For us, this was the final and decisive step on the road to industrialization," says Christopher Lämmle. Vehicle-specific or manufacturer-specific, proprietary inductive charging systems in small series were already available on the market. There are also systems for automated industrial trucks or forklifts, for example.
In other words: one system, many users. Lämmle estimates that the first systems based on the new standard will hit the market about three years after its official release. “In our experience, that’s typically how long it takes for a new standard to make the jump from definition to real-world implementation,” he explains.
MAHLE is working together with Siemens, among others, on its inductive charging system. Siemens is developing the permanently installed charging infrastructure, for example in private garages, parking garages or at public charging points, while MAHLE is developing the vehicle components, also known as vehicle assembly. The system essentially consists of three elements: the power electronics for energy transmission, the assistance systems, especially for positioning, and the integrated safety systems. For example, they detect whether a living creature, be it a crawling child, a sniffing dog or a curious cat, is approaching the charging system and then interrupt the energy transmission.
Users do not have to actively take care of the charging process: as soon as the vehicle approaches the charging point, the two system components interact and the energy transfer begins automatically when the vehicle leaves the charging point. "In the first step, we are industrializing a system with 11 kW charging power for the light duty sector, i.e. for cars," says Christopher Lämmle, describing the next steps. This corresponds to the output of today's AC wall boxes. "For the first phase of market penetration, we expect that vehicles will continue to have a separate component for fast DC charging by cable in parallel with the inductive system." This is usually done today with an output of up to 200 or 350 kW.
Users don’t have to actively manage the charging process: As soon as the vehicle approaches the charging point, the two system components interact, and energy transfer begins automatically once the vehicle is in position. “In the first step, we are industrializing a system with 11 kW of charging power for the light-duty sector, meaning for cars,” says Christopher Lämmle, outlining the next steps. This corresponds to the output of today’s AC wall boxes. “For the initial phase of market rollout, we expect that vehicles will continue to include a separate component for fast DC charging via cable alongside the inductive system.” Currently, fast charging is typically done with an output of up to 200 or 350 kW.