Wow! And you have 80% battery at the end of the day? You must be living right or something!
On my work Rezound, which is used often throughout the day, I am usually at around 30% by the end of the work day, but this depends greatly on where I am working and the signal strength I am getting, poor signal strength I am usually charging before the end of the day, really good signal and I am around 50% or so, on a standard battery