It's my personal theory that the G2 charges beyond 100% but displays a max value of 100% (e.g. at say, 105%). That would explain why, usually, that it stays so long at 100% after removing the charging source before it starts going down.
My guess to your question (if the above is truel) is that if you remove the G2 from the charger 5 minutes after reaching 100%, it might actually be at 105% (using a rate of 1% per minute). However, when wireless charging, the charge rate is MUCH slower, so that 5 minutes after reaching 100%, the battery is at 100% or maybe 101% because of the slower charge rate.
Disclaimer: purely guesswork. I imagine you have a Verizon device since you don't mention otherwise (since it's the only model with built-in wireless charging) but I use a universal Qi charging coil and the max input is 750mA even though the charger to the pad is 2.0A output, so it has less than half the charging speed (I'd say closer to 1/3 in my case).
