There seems to be some excitement growing around the subject of wireless charging, with the various industry associations, standards setting bodies and companies jostling for position. The names and groups include the Wireless Power Consortium, Alliance for Wireless Power (A4WP), Qualcomm, Samsung and Intel.
I remember getting a little excited about the topic myself a few years ago when a company called Splashpower Ltd. emerged out of Cambridge England. But the company and I were a bit ahead of the market and the company has disappeared.
However, the more I study the topic the more I am inclined to say forget it. Do the right thing and use a wired charger for reasons of ecology. That's because wireless charging is not as energy efficient as wired charging. Last I heard a typical wireless energy transfer efficiencies are about 70 percent going up to 80 to 85 percent with careful design, more copper and better shielding. But it is hard to imagine it ever being as efficient – or as green – as wired charging.
There is a counter argument that runs thus: If users of multiple separate chargers leave them plugged in 24 hours a day and 7 days a week, even when they are not charging an appliance they will each consume power. A single wireless charging platter that copes with multiple pieces of equipment, switched on and off appropriately could represent a power saving.
I don't buy it. Instead I would say do the right thing and plug in a wired charger for the time it is needed and then disconnect it.
There are parallels with the invention the standby button. Philips –which has now got out of consumer electronics – used to claim this invention and that it was a great boon to mankind because of the power it saved.
I reckon the opposite is true. Until the standby button was invented people turned off appliances that were not in use and I even unplugged them. Once the standby switch was invented televisions were left on overnight and sometimes are not switched off for months or years at a time, all the time drawing some power.
Finding enough energy to do all the things a global population of 7 billion wants to do at a cost it can afford is a major challenge to humanity so "wasting" energy should become one of the big sins of our era.
Of course, one person's waste is another person's convenience and yet another's necessity. But in general I would say do the right thing, and don't use an inherently inefficient technology when there is a more efficient established alternative.
P.S. This maxim also applies to writing inefficient software that makes unnecessary fetches from memory or carelessly uses processor cycles to achieve overblown functionality or graphics. But the authors of code for mobile applications at least have a commercial imperative to do the right thing.
Though in terms of energy efficiency, wireless charging is not that good. Under those cases where energy efficiency is not of major concern, it is still unforgettable.
1) In some situations, we cannot apply contact charging, for example, those electronics embedded in human bodies. To power those devices under these applications, wireless charging is, at least, one of the choices.
2) When a lot of charging devices are considered, the amount of chargers can sometimes be reduced with wireless charging. We need different adaptors for devices of different voltages. A wireless charger only provides the primary side coupling coil while the devices with secondary coils determine the voltages required. This caters for devices with different operating voltages.
3) For wireless charging, no connector and so, no plugging/unplugging mechanical reliability issue.
So, a small portion of wireless charging may still be required.
No 180 degree turn.
I was excited about Splashpower because it was a UK startup and something for me to write about in a novel area. Didn't mean I was going to use the product.
Similarly if a company emerged today with an innovative wireless charging offering I would be interested to learn about it and write about it.
I have designed wireless and it will never be as efficient as wired everything being equal. Wired can more easily detect load and shut itself down. If the manufactures can use a standard for wireless they could create a standard for a couple of common plugs for different power levels. I believe parts of Europe require common chargers for cell phones. Think of all the land fills saved and the energy saved in not making extra chargers. Also no EMI pollution.
All of you talk about the inefficiencies, but none have given any hard numbers. You are all going on gut, which is mostly good, but best you get some hard facts from an actual pad or pad company with each of the competing technologies (inductive or resonant, or etc) before you start spouting a religion.
I came across Splashpower right at the beginning as I used to work with its first first CEO. I agree that the potential of wireless charging seemed fantastic. They were talking about pads in coffee shops, hotels, bars, cars, bedrooms, kitchen worktops etc. The ability to walk into almost any room and drop all my devices on a pad was (and still is) very attractive from a convenience point of view.
I think it foundered, and possibly will continue to founder, on two things. One is the need for ubiquitous pads; the other is the need for universal and seamless interworking across products and manufacturers.
I suspect that the first will never happen due to the cost and the second because of competing interests. I am happy to be corrected by events on both counts!
I admit that I had not considered the "green" aspect before but it is clear that any wireless charging solution is going to be less energy-efficient (for all sorts of reasons - transmission loss and being left on all the time to name but two). Peter's aspiration to used a wired brick and always unplug it when not in use is admirable but 99% of us (myself included) will _never_ do it!
You can't violate the laws of physics. There is no way to wirelessly transfer energy that doesn't leak. And the larger the gap the larger the leak. A charging mat will have a large gap by necessity. And the leak does not become heat, it is a radio wave, that will leave the Earth taking its energy with it. The idea of charging a car or bus from the road scares me, that is a six inch, unsheilded gap! People talk about the convenience of these kinds of things (undoubtedly true), but we already must find an alternative to fossil fuels, and are struggling to find safe energy sources to replace them. We are also struggling to up our infrastructure to allow electricity to take over for fossil fuels. Now you want to add a 20% hit to that?