I had the same problem when I got my PRS-505 in December 2007. I use to see post about people readers lasting over 2 weeks and I thought they must never really read that much because mine never last that long. Then in December 2008, just 2 weeks before the warranty ran out, I could barely get 4 days per charge. I sent it back to Sony for repairs and they in turn sent me a new reader 2 weeks later. That's right, they did not repair it, they chose to replace it instead and charged me $29.
I read just as much as before but now my reader last OVER 2 weeks per charges; go figure!
