Charger not powerfull for MSI GE 72 ?

Hi,

I just got the MSI GE 72 - 2QF (970m - i7 5700hq) and I note that the battery discharges then I plugged the charger.
This only happens when I play big games like GTA 5, for 1 hour of games I lose about 5% battery.
Is that the charger does not would powerful enough for this pc ?

Thank you