Over saturating a li-ion battery is not a good idea. When you put the charger in the phone. The voltage shoots up. And says ready, but the battery is not ready, thats why, you can have a full change, and suddenly, it drops. Because that was a false ready. So the phone is saying battery is charged when it's not because phone cannot measure battery capacity, but voltage. They suggest charging the phone while turned off so voltages and stuff can balance. batteryuniversity.com/learn/article/charging_lithium_ion_batteries