Wireless Charging: Don’t throw away the cables yet!

Snip20151122_24.png If there’s one thing that is more messed up than any of you friend’s life or yours and much more complicated than any of your relationships or your friends’, its definitely the bunch of tangled wires in the front pocket of your bag and I am positive that we all can unanimously agree upon that. With a noble intent to solve this mess, the onset of wireless charging technology has commenced and we are starting to hear more and more about it. This is still the nascent stage of the technology and there’s no fixed standard or protocol that has been accepted as the most efficient way of charging wirelessly. This post talks about two different wireless charging standards, that are aggressively bidding for mass acceptance and eventually mass production.

Before I give a purview of the wireless charging standards lets talk about some of the concerns that need to be addressed for the user of this technology i.e 24 billion devices by 2020.

  1. Will the wireless charging pads/routers/docks be any more convenient to use than a USB cable?
  2. Will the time to charge be any better or even worse than a USB plugged to a laptop?
  3. Is the wireless charging accessory an add-on to the portable device or is it embedded in the internal device circuitry?
  4. If it’s an add on, then how heavy or easy is it to integrate?
  5. Is it a universal solution for mobile phones, wearables, laptops and other portable devices or do I need one for each?
  6. Do I want to be surrounded by more electromagnetic waves around me?
  7. Is it any more affordable or do I need to invest heavily into this technology?

These were just few of the many questions that are brimming at the top of my head. Lets take a look at the two different wireless charging standards that are evolving as potential solutions:

Qi Wireless Charging Standard: Qi is primarily based on the principle of electromagnetic inductance i.e.  powered by two coils of wire. The transmitting charging coil is driven by alternating current that produces an oscillating magnetic field, and induces an alternating current in the receiving coil located on the device being charged. This alternating current is then converted to  DC, thanks to Tesla, and wireless charging is achieved.


  1. Comes in two form factors: 1. embedded in the mobile device and 2. as an optional smart phone or battery pack case.
  2. Enables almost 5 W of power transfer.


  1. Necessitates a proper alignment of the mobile device and Qi Charging pad for maximum power transfer.
  2. The effectiveness varies with the size of mobile device and docking stations.
  3. The manufacturing cost for this mobile standard is pretty high, the mass production might not be a smart choice.
  4. Can only charge a single device at a time.


Rezence Wireless Charging Standard: Rezence is based on the principle of electromagnetic  resonance. The magnetic resonance is very similar to the electromagnetic induction technology, except that in the former the transmitting and receiving coil are tuned to resonate at the same frequency, better suited to loosely coupled coils.


  1. More suitable for energy transfer over relatively larger distances.
  2. Relatively less sensitive to misalignment of charging dock and portable devices.
  3. Can charge multiple devices simultaneously.


  1. Requires more power supply to the charging pad/station for more effective power transfer.
  2. The manufacturing cost is pretty high.
  3. This technology has not really penetrated the market yet and is still in the development phase.


While Qi does have an early mover’s advantage, the limitations on efficiency and manufacturing cost will become a bottleneck in this charging standard becoming am industrial norm. On the other hand, Rezence, based on magnetic resonance, is a much more practical solution, yet not scalable as the manufacturing cost is still high. There are other evolving methodologies like the Wattup Technology , that uses a radio frequency system to transmit power up to 15 feet from the charging station. I think its too early to place a bet on which technology will win the race or will it be a combination of many. However, the need of the hour is to bring down the manufacturing cost without compromising the power transfer efficiency.

Exciting times lie ahead!





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