MacBook Pro USB port provides more current in Mac OS X than in Windows

Question

I have a MacBook Pro with both Mac OS X Lion and Windows (under BootCamp) installed. While in Windows, I tried to charge my iPad 3 via the USB port. The iPad says "Not charging", but really, it does, just super slow (4-5% per hour). The reason for this is that the iPad requires 2.1 A of current, but a standard USB port provides 0.5 A.

However, if I switch to Mac OS X, the iPad states that it is charging and it does at a rate of about 10% per hour.

The only takeaway from this is that either OS X puts out more current on the USB port or that it recognizes the iPad and acts accordingly.

Can someone provide more information on what is actually happening?

Answer 1

Apple has a support article which covers this question nicely. They explain how an Apple device can request additional power when their operating system is running which allows the iPad and other higher-power peripherals to charge more quickly under certain conditions. They specifically state that a USB port will not provide more power than usual when Windows is booted through BootCamp.