In article , Helmer Bengtsson
wrote:

The move to USB 3.0 only affects charge rates connected to a PC.

2.x is limited to 500mA while 3.x is 900mA I think.

originally, but the battery charging spec allows for more current.

Both standards use 5V, but 2A AC chargers often run a bit higher at 5.3V.

no they don't.

5.3v is outside the usb spec.

The chargers don't directly adhere to either USB spec and basically
trigger fast charge the same as before, by shorting out or putting a
fixed resistance between the data pins.

My old HP TouchPad USB 5.3V/2A charger with 2.0 cord charges my Note 3
just as fast as the Samsung 5.3V/2A adapter with USB 3.0 cord does.

If you look closely, you'll notice that the "USB 3.0" Samsung charger
doesn't actually have the extra 3.0 pins, it uses a 2.0 port. That's
because for pure charging devices the standard doesn't matter, only the
current and voltage rating and that it shorts the data pins.

then it's not compliant in more ways than one.

it's supposed to negotiate the power over the data pins.