My battery is not charging on my acer laptop

Is it charging but not holding a charge (running out of power very quickly), or is it not charging at all (as though it wasn't even plugged into the outlet)?

There are two possibilities:

1 - defective AC adapter.

2 - Battery cannot hold charge. How this can happen? Always using AC adapter when using laptop. AC adapter is constantly charging the battery. Battery is supposed to be fully charged and discharged (just like you cellphone). Happened to me, a mistake that cost me $250US to replace the battery. I only have the battery plugged in when on the go, most the time battery is removed.

Either your adapter is bad or your battery is bad. You need to get them tested.