I have a 17" MacBook Pro that I use as both a desktop and a portable computer. I will have days when I continue to work from my desk at home and the macbook pro could be plugged in for 5 days. I notice the longer I have my macbook pro plugged into the wall, the battery charge dips from 100% to 99 than 98 than 97. I have had it go all the way to 91% once. Why does it do this? Is this normal or is there something wrong with my battery? Btw, I had the battery replaced with a new official apple battery (not a generic third party battery), 8 months ago, so my cycle count is about 105 and in the 'System Information' app, my battery status shows up as 'normal'.