RBP 2017 keep shutting down on heavy load game

hi guys, so im experiencing this sudden shut down on RBP 2017 with gtx 1080. my battery had bulged up a while ago, and i have to play rely on to the 250w charger. i thought its possible since other Laptop can do that. but since then my RBP experiencing sudden shut down on heavy load game. after around 5-10 minutes of playing, the Laptop shut down for no reason. i checked the Temperature and its around 80 so i think it should be fine. is there any Chance that my adapter not powering enough Juice anymore to my RBP , so its broken ? or should i just plug in a new battery ? thank you and best regards