What’s the Difference Between Qi and Other Types of Wireless Power Transfer? (.PDF Download)

Apple announced that its iPhones, AirPods, and other accessories will all include Qi (pronounced “chee”) wireless charging. The Qi standard is one type of wireless power transfer, and certain to be a popular one due to Apple’s adoption. However, other types of wireless power transfer, such as AirFuel Resonant, proprietary near-field magnetic coupling (NFMC), radio frequency (RF), and ultrasound offer different value propositions.

The purpose of this article is to explain the key differences between Qi and other types of wireless power transfer technologies. The focus is on interoperability, adoption, use case, technology readiness, and safety and regulatory.

Interoperability

The No. 1 value-added differentiator for Qi is interoperability. If you see the Qi logo on a product, it is Qi-certified. Qi-certified devices (e.g., phones) are guaranteed to work with Qi-certified transmitters (e.g., charge pads, enabled autos, embedded furniture).  This is important in the world of consumer electronics, where users can expect to have Qi transmitters in common locations throughout their daily life: home, car, office, coffee shops, airports, hotels. For the foreseeable future, the vast majority of consumer electronics will be Qi devices due to the benefits of interoperability and leveraging a common infrastructure.

AirFuel is another standard that offers interoperability using a different type of protocol, frequency, and process than Qi. Theoretically, AirFuel promises the same interoperability benefits as Qi (all AirFuel devices will work with all AirFuel transmitters), but the current reality is that Qi has scale via adoption that AirFuel can’t match.

Proprietary NFMC is, by definition, “proprietary” or “non-interoperable” with other devices.  Proprietary systems don’t make sense for consumer mobile devices, but make a lot of sense for non-consumer devices like medical tools/devices, commercial-grade equipment, industrial electronics, unique form-factor devices, etc. There are at least three specific reasons why products may not want interoperability:

1. Device security

• Eliminate workers from charging their work devices in a public space and forgetting them
• Exposing devices to data vulnerability through public infrastructure

2. Safety

• Safety hazards caused by using personal devices on work equipment (e.g., delivery drivers charging personal cellphones on auto transmitters meant for handheld inventory trackers)

3. Unique use cases

• The Qi and AirFuel standards have specific use-case constraints that don’t suit all applications