How to Preserve Your Phone's Battery
My dad is a mobile software engineer who has worked for Motorola, Blackberry and other companies and this is what he told me:
★ Charging your phone overnight is OKAY. The rumor that doing that damages your phone is a myth.
★Letting your phone die is what permanently ruins your battery.
★Having to fully charge from a very low state ruins your battery.
★When your phone reaches 20% charge it or turn it off until you can charge it.
★ Between 80%-50% battery is the best place for your phone to be daily to ensure good battery life.