When it drains quickly, go to Settings/General/Battery. Take a screen shot. Tap the graph and take another screen shot. Post them here. (See
How To Post Screenshots on Android Central.) (Please create a free account here, so you can continue the discussion in this thread.)
There are a few possibilities as to why the battery is draining so fast (using a Samsung charger isn't one of them), so instead of throwing all of them at you, if we see the screen shots we may have a better idea of what's causing your problem.