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I have owned one model of smartphone with wireless charging, Nokia Lumia 920, which had a (optional) wireless charging pad, DT-900. That pad (which, b.t.w, has a proprietary 12v power supply with round plug) worked well for that phone and the phone was not very "sensitive" to the placement on that pad. Recently I have purchased another phone that is capable of wireless charging, Nexus 4 from Google/LG. Now both the Nexus 4 and Nokia's pad are supposedly compliant with "Qi" wireless charging format, however I had some issues with both of these - Nexus 4 was extremely "sensitive" to the placement on this pad, you had to discover the "sweetspot" through some "trial and error" and even a very slight "displacement" would cause the Nexus 4 to "cycle" between charging and discharging every few seconds. And the pad itself only has a single tiny LED which is not very helpful - it is either "on" or "off" and is located on the side of the plate which is pretty inconvenient. I got tired of that annoyance and got another "Qi" wireless pad, from Anker - it is available at places like Amazon:
http://www.amazon.com/Qi-Enabled-Single ... B00BHSDEDO
It doesn't come with its own power supply - just a plate and the USB cable. It is also pretty large (which is good) and has 2 LED indicators - one shows that the plate itself is receiving the power and the other shows the charging status for the phone itself and both of these indicators are located on top of the pad which is very convenient. However, when I tried to use Nexus 4's included power supply (which seems to be rated at 1.2A) - the "charging" indicator on this pad would flash in red color, indicating that the phone is not receiving enough current. Luckily I also had a spare power supply from iPad, original one, rated at 2A, and that worked perfectly with this pad - my Nexus 4 now charges properly (the "charging" indicator flashes in green color, like it should) and the phone is not extremely "sensitive" to the position on this plate (unlike with crappy Nokia's plate).

Hopefully this information will be helpful for anyone looking to get a phone with wireless charging (which in itself is very convenient), and if you have also tried different "Qi" pads with different phones - you're welcome to share your own experience with them.

Thanks for the info. Things like this are why I'm still hoarding most of my iPad AC adapters, despite no longer using the iPad itself. It's hard to find an adapter that will crank out 2+ Amps over USB reliably, and EVERYTHING loves more amps when charging.

Odd. My experience with the DT-900 has been pretty good. I was given one as a gift to use with my HTC 8X, and I was actually surprised at how well it worked. The phone body can be rotated at pretty much any angle and it will still charge. The placement laterally is a little pickier, but it still has a couple of centimeters of leeway in all four directions before it won't charge.

Maybe HTC did a better job placing the receiving coil in the phone itself? Though it seems hard to believe that they would get something right that Nokia and LG have apparently struggled with.

Phone chargers are generally ~1A whereas tablet chargers are ~2A, and the wireless pads are going to be spec'd for the worst case I imagine. The various wireless charging pads and phones/devices seem to vary quite a bit wrt to the size and orientation of the "sweet spot." I seem to remember a review where they explicitly tested this (Anandtech maybe?) but I can't find it ATM.

Forge wrote:

Thanks for the info. Things like this are why I'm still hoarding most of my iPad AC adapters, despite no longer using the iPad itself. It's hard to find an adapter that will crank out 2+ Amps over USB reliably, and EVERYTHING loves more amps when charging.

That was very true, but over the past six months or so things have improved. You still have to be careful to look for USB chargers that explicitly state they output 2.1A (if they don't say it, they almost certainly don't do it), but they are far more widely available now and you don't pay much of a premium for them anymore. Heck Home Depot now stocks 2A adapters for home or car for $10 - $15, and you can find them at WalMart and Canadian Tire, etc too. (As always, of course, the cheapest option may not be your best bet in the long run).