I've charged to 98% one time, very briefly but normally 97%. If you charge via USB whether it be laptop or A/C your values will differ depending on how long you leave it charging. As you know after awhile it will begin to lose the charge, hence the message given when you unplug after a full charge, "disconnect to save power".

I have an extra battery that I will just leave in for days at a time in the charger and usually on the weekend or whenever I replace the battery, it's always @97%.