How to check if my battery is OK? I use my phone mainly for wifi use and I know it is a battery hog. However, what I would like to know is how much time it takes for the battery to charge. I guess it is supposed to take like 4 mins to charge 1%.  

I plugged in my phone at 11% battery at 1.00 am and at 7.00 am it was still charging at 65%. What seems to be the issue here ?   

Update 1:
Going by a comment on the post here, it is because of the sequence in which I connect the phone to the charger. The comment goes as follows:  


  Hi I think I found the problem as to why mine was charging slow.  Make
  sure the USB end is unplugged from the charger BEFORE plugging the
  phone end. After plugging into the phone, plug the USB to the charger
  while the charger is into the wall. Not sure why but the sequence is
  Important and affects charging rate big time.
  
  Alex  


This is in the manual, too. Unsure as to what the internal mechanics of the charging are.
I think what matters most is the amperage of your charger. If you are plugging your phone into a computer then it is limited to 500mA. A charger for the S3 will typically provide 1A to 2A I believe.

One more thing which may be going wrong is battery hogging applications. If you switch your phone off and then charge, by how much does your charging time lessen down?