It seems like iPad gained popularity again the other day not because of its great specs, but because of consumer complaints regarding a battery charging issue.
One of the technical specs of iPad is the built-in 25-Watt-hour rechargeable lithium-polymer battery that can be charged via power adapter or via USB from the computer.
The problem now is that some iPad users encountered a problem which says iPad is not charging in USB. This actually happens when the iPad is connected to under-powered USB port which provides insufficient power to charge the iPad.
Quoted from Apple support page:
The USB ports on Apple computers provide 5 V (Volts) and 500 mA (Milliamps) to each port, regardless of whether the port is USB 1.1 or USB 2.0. This is in compliance with USB specifications. On some newer Intel-based Macs, such as the MacBook (13-inch, Late 2007), when a device requiring more than 5V and 500mA is connected, the port with that device connected to it becomes a high-powered port capable of offering up to 1100 mA at 5 V. That port will continue to operate as a high-powered port until the device is removed.
What you need to do?
Basically, users have to utilize the 10-watt USB adapter included in the iPad. The adapter will be able to fully charge the iPad. Or you can connect your iPad to a high-power USB 2.0 port. Apple added some charging tips saying:
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.