It is a voltage issue. Apple supplies a power supply specifically designed to charge the iPad. Your USB port on your computer might not put out enough voltage. You need at least 10W of power.
Also, your computer might go into standby or sleep and that affects charging.
--- In iPad@yahoogroups.com, Wyldceltic1 <wyldceltic1@...> wrote:
>
> One night I plugged my iPad 2 to my iMac and let it sit over night. It looked as if it was not charging, but when I left it it was at 45%. Next morning it was at 100%.
>
> *I* think it DOES charge, but it is dog slow.
>
> On Sep 26, 2011, at 11:29 PM, phyllis wrote:
>
> > I just got my IPad2 yesterday. When I plug the cable from the IPad to the USB it says not charging. If I plug the cable into the ac adapter it charges. I tried the cable that came with it as well as the one for my IPhone. Does it not charge from the USB of the computer like the IPhone does??
> >
> > Phyllis
>
