Originally Posted by labpedro
not sure if you have tried this, but make sure the usb charger is plugged into the mains charger all the way in...mine was the same, saying usb charging and it was the cable itself
Yep. For some reason LG decided to go with a USB charger for the phone rather than straight to the mains...
Mine takes about 3 hours to charge fully, when plugged in, locked and connected to WiFi. You have to remember, the G3 has a big battery, bigger than some other phones, so you have to expect it to take longer. I plug it into my USB 3.0 port on my PC when I'm on it and it seems to charge faster (Although my motherboard has the option to turbo a port for charging so it may just be me).