There are several reasons why your phone’s battery does not charge properly. Check each individual possibility to exclude all sources of error.
- Is the charging cable defective? Try a different charging cable.
- Turn off your phone and remove the battery. A “hanger” is always possible.
Fully discharge the battery until the phone turns off and try charging again.
- Try another battery compatible to the same smartphone to find out if it is possibly a software problem.
It might help to reset the smartphone to factory settings. Some bugs in the software are fixed. If all this does not help, contact your provider/store and explain your problem.