LG G4 :: Phone Died While Charging

I plugged the phone in at about 15% and I started to play a little game. Not sure how long I was playing maybe 10-15 minutes. When I looked the battery was at 6%. Phone was on the charger! I then exited the game and put the phone down and started some cleaning. About 10 minutes later I went back and the phone was down to 2%!!! I couldn't understand what happened. This is exactly what was happening with my s3 before I switched to this phone. I unplugged the phone to make sure it was plugged in correctly. When I unplugged I got the notice that there was no power left and it shut down. I can't even tell what was running or if the game was still running.