why does my phone discharge when charger is plugged in?

[AC Question]

my phone shows that its charging when the charger is plugged in, but the battery percentage instead reduces.

 

[belodion]

A faulty charger, lead, USB port or battery, perhaps.

 

[B. Diddy]

Welcome to Android Central! Does this happen when plugged into a computer USB port only, or also when plugged into a wall outlet?