Why is battery level moving from 0% to 100% immediately I plug it

I have been using a samsung galaxy tab 2 for sometime. I discovered that when the battery is low and I plugged it into the socket to charge, it moves from the low battery level to 100% charge almost immediately. I thought it was because the battery is getting weak,I bought a new charger and a new battery. After the new battery was installed, the issue persisted. Am still experiencing it now, d battery level was 11% before, as I plugged it into the socket, went straight to 100% charged. Please what. could be the issue and what can I do? will be expecting your response. thanks

Ayo.