Does the G3 require a replacement back to work with a Qi charger?
If your battery door has four pins on it like in the picture below, then it will do wireless charging.
Otherwise, you'll need to buy
the replacement back (just an example, I'm sure it's cheaper elsewhere) or something like this...
http://www.amazon.com/LG-Wireless-Ch.../dp/B00MMRWS5E