I left the new PB charging all day to make sure I didn't mischarge the battery and screwup its lifecycle like the manual tells you. However, when I unplugged it after about 8 hours it showed a lifespan of about 4 hrs and 3minutes initially. 3 minutes later that was downgraded to 2.5 hours of life, then 2.2. Then when I turned down the brightness (full brightness before) it went up just below 3 hours. I thought the new line of PBs got an extra hour of juice left? This is on par with what my 2 year old 12" PB got after months of use. Will the battery get better with a couple of depletions/charges?