When your tablet is off, blow into the charging hole, then use an open safety pin to dislodge any dust or dirt. Then blow again into the hole. Also ensure that the charger is clean. That should take care of your problem.
Acer is proud to announce the promotion of Philetus to the ACE team. Philetus has been a member since March 2013 and has shown the skills and patience required to be a member of this exclusive, invite only team of experts. Congratulations Philetus!