"The fastest way to charge your iPad is with the included 10W USB Power Adapter.
iPad will also charge, although more slowly, when attached to a computer with a high-power USB port (many recent Mac computers) or with an iPhone Power Adapter.
When attached to a computer via a standard USB port (most PCs or older Mac computers) iPad will charge, but only when it's in sleep mode.
Make sure your computer is on while charging iPad via USB. If iPad is connected to a computer that’s turned off or is in sleep or standby mode, the iPad battery will continue to drain."
I have the same charging problem as iHiba.
My iPad is two years old and has had light use.
I am using 2 different (OEM) 10 watt ac USB chargers that, until recently, fully charged the iPad 2 in less than an hour.
Now, it creeps up the charge scale all day long and takes 8 hours to go from 24% up to 64% charge.
I tried restarting the iPad (as was suggested in some other forum) but the condition seems to remain. (It's a little faster after the restart, but it's like watching radishes growing from seeds.)
Thanks for any thoughts.