I know most USB 2 ports don't have the necessary current to charge it, but USB 3.0 is rated at 900 mA. Even though its not capable of syncing at the higher speed, will it be compatible with charging at a higher current?
USB 3.0 is rated for 1.5 amps in low or normal data speed, and 900mA at highest speed. Dedicated charging ports go to 2.5 amps, but are useless for syncing, as they do not support data. USB 2.0 ports can certainly charge the iPad if rated high enough. Some will charge only when the iPad is asleep.
but when my current PC won't charge the iPad, my only options are to buy a high powered USB 2.0 or a normal 3.0 card. I'd think, if its compatible, I should buy the 3.0 just so its more future proof.
Just an update:
Since this thread, I've tried using both an addon USB 3.0 card (with power boost) and a built in USB 3.0 motherboard. Both times the iPad claims it's not charging when plugged in but it's definitely still is. I'd say it's about 1.5x faster than standard USB 2.
From what I've read, the iPad doesn't claim to be charging unless connected to at least 2.1 Amps. Because USB 3.0 is only 0.9 Amps, the charging icon isn't triggered. I'm not sure how new Apple computers trigger the charging icon though because I very much doubt they have USB with that much current. I can only imagine the iPad recognizes the computer is made by Apple so artificially triggers it (even though it probably charges at the same rate).
