I've noticed that if I recharge my cell phone battery to 100%, then take it out, and put it back in and put the phone back on charging, it resumes charging the battery and continues to do this for upto 30 mins, despite having just received a 'battery full' message about 30 minutes ago.
Why does this happen? Is this normal or does this indicate that the battery is degrading?
It is a Li-Ion battery.