Is there any relationship between the speed of the charging and the USB ports ?

Hey ,all guys, a week before I've gotten a Christmas gift usb 3.0 hub from my brother. I have just used it for several times on my Toshiba PC ( Windows 7). It works great generally. The transfer speed firstly presents very approximate to usb 3.0. Later I started to use the charging function which seems also brilliant to me. That's the premise of my issue. Then two days when I visited my cousin, she borrowed my hub and called me last night that the charging port is not useful only for her new Ipad Air. She said it acted no sign first and then started charging slowly. I am a little confused about the case because I have no idea about the Ipad Air.

Has anybody helped me to analyse the possible causes ? Or is there any relationship between the speed of charging and the usb port or the devices they connected to ? I would love to try any proposal.

 

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John.

 

The iPad Air will charge slowly from a USB port because if it charged at the same rate as the iPad charger, it will melt your hub (OK, overdramatic but the point is that it's beyond your hub's capabilities).

There's a maximum limit to the amount of current your laptop or hub will allow a USB port to draw - this is part of an international standard, and devices which try and draw more for any reason will only be allowed to draw as much as the hub/laptop can deliver.

Most tablets which charge via a USB port are capable of drawing a lot more power to charge than a standard USB port. So when they're plugged into a dedicated (proprietary USB) charger they will charge fast. Via standard USB, slow.

 

Some devices while they use usb to charge are not really meant to be charged over a traditional usb port, normally they will have a wall plug to usb converter that puts out much more power than a normal usb port.

Tablets are especially prone to this issue.

Ipad Air has lots of pages/discussions about this here is just one of many: https://discussions.apple.com/message/23622600#23622600

Does this USB 3.0 Hub have its own power supply? I would hope so, so make sure its being used.

 

Another thing thats commonly overlooked is the charging cable itself. Not all cables are the same.

Avoid those cheap, long, thin cables. A thin 28AWG cable at 2 metres will roughly have a 34% drop in voltage, so by the time it reaches the devices it would be 3.3v instead of 5v. This will result in slow charging or it might not even charge at all if the devices senses its too low.

You want a short cable thats at least 26AWG copper core.