that's really common (at least in my life)
firsto of all download "Galaxy Charging Current"
and plug your phone in and check how much mA flows it should be 999mA or more
i'm kinda 90% sure that it will be less than that so there are few things that effect that
- Bad or $@$*!& charger
- Bad or $@$*!& cable, or it's really long and it's resistance is big
- some junk or crap in your USB port
- crap micro USB Male connector
So try diffrent USB ports becouse if you draw current from an resistor (your cable) you'll always have so called Voltage drop it could be only 0.2 or 0.3v but that's enaugh to mess things up
USB should be 5v and it kinda is so many manufactures make it 4.2v (maximum) and after it drops you have 5.0v on your phone but if it's 4.8v and it drops to 4.6v you phone won't be happy
try short lead on few other USB ports
if your current is like 999mA or more and it still drops than we dealing with compleatly diffrent story just let me know and hit helpfull if i helped