laptop goes off when playing a game while plugged and battery is removed

Hello,

I'm having a problem with my Dell Inspiron 14 that I bought just 2 weeks ago. In order to prolong my battery life, i often remove it and plug the laptop onto a power source when i'm at home. Although the problem doesn't happen always, for the 2 weeks that i have this laptop with me, i already experienced the problem for 5 times in which the power went out when using it for about an hour or two when playing games like DOTA 2 even though it is still plugged on to a power source. It happens as if the plug was pulled, but it wasn't. Can someone help me because I don't know why that happens? I am sure it's not the socket nor the power source because the plug is tightly inserted onto the power source. Any help will be highly appreciated. Thank you.