I've read that a smartphone owner has to have a completely different attitude toward phone charging -- that keeping the phone on the charger is a good idea for smartphones. Yet when my battery is fully charged, my "full battery" screen comes up and tells me to unplug the phone. Why? It's so much more convenient for me to leave the phone on the charger than realize the battery has drained just when I want to use it. Is there a reason why it's not a good idea to keep charging the phone when the battery is fully charged?