aao 532h-2dr wont fully charge

hello guys. i'm new in this forum and i own an acer aspire one 532h-2dr. bought it May last year. I know some members has posed this problem before. I just want to try maybe others has found a fix or update on this one. My charging has been perfect ever since. I would use the laptop on its battery and plugging it only when it gets low. charge it to hundred percent then unplug it again. Until recently, i think around last month that it would not fully charge. Charge indicator would indicate 86% and the icon stays orange. so i would leave it plugged for a few hours to see if it would reach 100% on or off. No luck. i even tried plugging it overnight thinking that the charging was very slow but still no luck. what could be the problem? could it be that my battery is slowly wearing down? but why wont it charge to a 100%? it would be understandable that my battery is wearing down if it charges to a hundred percent but it would last only for 3hrs or more. coz when it was new, i would get 5hrs on it fully charged.