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.
6.3L V8 451hp@6,500rpm and 443 lb-ft@5,000rpm, 7-speed SPEEDSHIFT MCT, aux oil cooler, 14.2" rotors & 6-piston calipers front, 13.0" rotors & 4-piston calipers rear, 30% LF LSD, 18" AMG wheels with Continental ContiSportContact 5P