Comparison of charging currents (LG vs normal chargers)
This information might be out there already, but after noticing the LG charger works much faster at charging my G2 than a Nexus 7 charger, I did a quick test using CurrentWidget to record the charging currents for each setup to see if it's the special LG USB cable or the LG charger base / AC travel adaptor (or a combination of both) which is needed to enable the fast charging.
It's been mentioned here before that there are extra non-standard pins / contactors on the LG USB cable which presumably are used to deliver higher charging current, but it seems that there is nothing special about the LG charger base / AC travel adaptor which use these. Using a standard generic AC charger with a USB port on it is enough to charge the phone quickly as long as the LG cable is used. (and provided its rated for a current output >1.8A)
LG charger + LG cable ......... 1600mA
LG charger + standard cable .... 250mA
2A charger + standard cable .... 270mA
2A charger + LG cable ......... 1600mA
(Tested using D802 running Mahdi Rom 07/29)