There are long discussions about this.
by R. Proffitt - 9/14/12 7:17 AM
In Reply to: Lithium Ion battery in cell phone: How often to charge? by Papa-n-Lola
But if you stand back, you find that cell phone users on average get more life from the battery than say a laptop user. Many think it's because the cell phone user keeps the battery topped off. In other words, plug it in when you can.