My Belkin powered hub gives me trouble with the iPhone and the iPad, I have to connect these two directly to my PC and they charge with no problem. I've also found this issue running portable HD's without a power supply, the USB hubs don't run them well.

Using a pc. In fact it is a usb slot in my Dell monitor. jim_joh

Originally Posted by gjperera

My Belkin powered hub gives me trouble with the iPhone and the iPad, I have to connect these two directly to my PC and they charge with no problem. I've also found this issue running portable HD's without a power supply, the USB hubs don't run them well.

I've never had good results from Belkin products. It all seems to be overpriced junk of questionable quality.

I have my ipad connected to my imac so no usb problems, however when using a pc sometimes there's always one port on a tower that acts up, system usb cards can go bad at times requiring them to be replaced.

Here is the official Apple tech article on this:

iPad: Charging the battery

• Last Modified: April 04, 2010
• Article: HT4060

Summary

iPad has an internal, rechargeable battery. To charge the battery, try the following:

• Connect iPad to a power outlet using the included cable and the 10W USB power adapter.
• Connect to a high-power USB 2.0 port using the included cable.

Note: Some USB 2.0 ports and accessories do not provide enough power to charge iPad. When this occurs the message "Not Charging" appears in the status bar next to the battery icon.




Products Affected

iPad

An icon in the upper-right corner of the screen shows battery charging status and approximately how much charge is left in the battery. If you charge the battery while syncing or using iPad, it can take longer to charge.
Rechargeable batteries have a limited number of charge cycles and may eventually need to be replaced. Battery life and the number of charge cycles vary by use and settings. For information on how long the battery is expected to last between charges, see the iPad Technical Specifications.
Charging Tips

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.

Additional Information

If iPad is very low on power, it may display one of the following images indicating that the device needs to charge for up to ten minutes before you can use it. If the device is extremely low on power, the display may be blank for up to two minutes before one of the low-battery images appears. If you don't see the white charging or plug icons, try connecting to the 10W power adapter.

When charging iPad using a computer's USB 2.0 port, make sure the computer is plugged in to power and not in standby, sleep, or hibernation mode. iPad does not charge when connected to an older accessory that only supports FireWire charging. When connected to these accessories, iPad will display the following alert:




"Charging is not supported with this accessory."

Source: iPad Charging the battery