iPad 2 can’t charge from an USB 2.0 port, did you know that? When you connect your iPad 2 to a PC with USB 2.0 ports, which can easily charge your iPhone (or most phones with USB connector), you will see a small ‘Not Charging’ notification next to your battery icon.
It does not however happen when you connect your slate to the 10-watt rated power supply which comes with iPad. Is it true, that iPad 2 won’t charge off USB port then? Not quite!
The truth is, it WILL charge, just not as fast. Even Apple itself admits, that iPad 2 is going to charge its battery despite the ‘Not Charging’ sign, but it depends on what you do while charging. For example, if the device is in stand-by, the battery will slowly but surely regain its power. Its all about the current rating: normal USB port has to supply at least 500mA of current at 5V. iPad 2 power supply is able to beat that specifiction – it provides 2A current. It is possible, that some Apple USB hubs (for example the one built in in 27″ iMac) can provide similar current, thus enabling the iPad 2 to recharge at full speed.