My power supply has no idea when it's connected, or if I'm using a battery often times.

When I plug in my laptop after it's dead is the almost only time it functions as intended. The rest of the time it's confused. When it charges, it just thinks it has a full battery and, after hours of charging, if I implug it, the computer dies. However, if I turn it on afterwords, it works fine. The read out works appropraitely then, and after it dies or if I plug it in during that, it will work again, but bringing it to full charge causes the same issue.