I purchased the 66i about 2 weeks ago. Since then, I've used and charged it about 6 times. 4 times out of 6, the charge reaches 99% and remains there regardless of how long its left charging (Usually over night)
I should add... Before proceeding to charge, I turn the back light to 0% then turn off the device so the only thing displayed is the battery logo with no backlight consumption.
This brings up another point. Why does the backlight remain at the setting left prior to turning off the device for charging? That's not very efficient. You want the least amount of battery drain while unit is charging.