Where in the Nexus 4 is the wire wireless charging coil? I've just received a "smartfox qi" wireless charger as a gift, but it won't charge my Nexus 4 despite its indicator light turning on, and the Nexus 4 says "charging wireless". Still, it doesn't charge, the battery graph shows a power depletion just as if it were just lying on a desk.
It's running stock 4.2.2 without a case. 

The charger has the exact same dimensions as the Nexus 4, so I just placed it exactly on top. I'm thinking that the wireless coils didn't match up well enough. So my question is:

Where in the Nexus 4 are those charging coils? How do I have to place it to ensure maximum-efficiency charging?

Bonus questions:


Wireless charging heats up the Nexus 4 a lot. Is this really healthy? Won't it significantly reduce the lifetime of the (non-replaceable!) Nexus 4 battery?
What specific product would be a good recommendation, specifically for the Nexus 4?
The charging coil is embedded into the back panel of the phone and is located directly over the battery, as shown in steps 7 and 8 of IFixIt's teardown.
The battery isn't quite non-replaceable, as the above mentioned teardown shows.  It's somewhat involved to replace it (you'll need a Torx screwdriver, a Philips screwdriver, a plastic opening tool, and some patience), but it's perfectly doable.
If you're wanting something that will work for sure, the official wireless charger would probably be your best bet.  However, it's not exactly cheap at $50.  I personally use this charger with my Galaxy S3, which I added a wireless receiver to.  I find it works well and charges right through my lifeproof case.