05Aug2010

iPad not charging but charging on USB

The reason the iPad doesn’t charge through most USB ports is due it requiring 10W of power to charge it

Here’s what we know so far through reports and our own tests:

iPad charges just fine through the wall charging brick and accompanying USB data cable
It charges just fine when connected to USB ports on iMac, MacBook Pro
It does not charge correctly when connected to a PC
It does not charge correctly when connected to an older MacBook Pro (pre-Unibody)
It does not charge through USB hubs, regardless of what the hub is connected to (PC and MAC)

There’s a few more details to this story.

The iPad actually will charge from a normal USB port, but not while the screen is on. If you hit the sleep button it will start charging, you just can’t tell because the screen is off. As soon as you turn the screen back on, it says ‘not charging’ next to the battery. Brings to mind the classic refrigerator light dilemma.

Apple has published guidelines about charging an iPad here