There are well known problems with Android OS and the reported maximum battery capacity. This maximum capacity is used by android OS to know when the battery is fully charged.
Advanced Battery calibrator will fix this problems and make Android OS see your real battery capacity allowing it to be charged to its real full capacity.
Advanced Battery calibrator contains some proprietary tricks that allow to a little range of devices use this application without being root. You have to take into account this only works for a 1% of devices more or less but it is something to try if your phone is not rooted and you need to calibrate your battery.
Advanced Battery Calibrator works specially well with its sister app "Battery Life Repair" and it has been designed to take full advantage of it by sharing information between both applications. If you want to keep your battery healthy use both applications and take advantage of its integration.