My Acer Aspire 4752 turns off when charger is unplugged

Hello!

This problem has just recently occurred. My batter pack is charged at 100% and even says so by my computer, however I tend to just let my power cord stay connected at almost all times (bad I know but it's a habit). So afterwards, I removed the charger from the laptop and my laptop suddenly turned off. When I plugged it in again, it turned on (after I pressed the power button). I noticed that when it opened, it's the same as when you open your laptop after automatically shuts down due to critical battery. An hour later I moved the laptop and had to unplug it from the charger; doing so cause the laptop to shut off. Any help would be great.