Re: USB ports on recent Macs can supply more than the USB standard power[was Re: IPad isn't charging: what the heck!]

2012-11-09 Thread Christopher-Mark Gilland 

Aa, ok, that definitely does explain a lot.

Thank you kindly,

Christopher-Mark Gilland.
Founder of CLG Productions

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- Original Message - 
From: "Esther" 

To: "Mac OSX & iOS Accessibility" 
Sent: Friday, November 09, 2012 4:25 PM
Subject: USB ports on recent Macs can supply more than the USB standard 
power[was Re: IPad isn't charging: what the heck!]



Hi Chris,

You wrote:

• So I wonder then why the macbook would charge it but not any windows 
machine?  Do macs tend to put out more vultage on their u s b ports?  Wonder 
what the amount of ampiers is it outputs.


The answer is that the standard USB port specification doesn't provide 
enough power to charge iPads.  That's one of the reasons that all the early 
generations of iPods (way back before the iPhone or iPod Nanos) used 
FireWire connectors.  But they moved to USB connectors when iPods became 
popular on PCs, and the lower power draw of these devices made that 
possible.


Recent model Macs are designed to detect when iPods and iOS devices are 
connected that require more power draw to charge than the default USB 
standard adopted by most PCs.  Depending on the load of what else you have 
plugged in, they will attempt to provide it.  Macs made before 2007 do not 
have this capability.  Here's a quote excerpted from an iLounge article:
• "Charging your iOS Devices on a Mac or PC" by Charles Starrett, September 
1, 2011

http://www.ilounge.com/index.php/tips/comments/charging-your-ios-devices-on-a-mac-or-pc/


On Macs newer than 2007, all your USB ports should supply at least 1100 mA 
of charging power to any device—such as an iPhone or iPad—that needs it. The 
extra power is doled out on a first come, first served basis, so the first 
device you plug in is virtually guaranteed to receive the maximum amount of 
power, while later devices are less likely. If you have a Mac that was built 
this year, it might even support full 2.1 Amp fast charging of the iPad. Mac 
users also have a very simple way to check how much juice each device is 
receiving. Simply go the the Apple menu, select About This Mac, and hit the 
More Info… button, which launches System Profiler. From there you can select 
USB from the sidebar under Hardware, and select the device you want to check 
on. It’ll show you the Current Available, the Current Required, and the 
Extra Operating Current—by adding the Available and Extra Current together, 
you’ll get the current power output for that port. For more info, see:

http://support.apple.com/kb/HT4049


The Apple Support document provides more specific details, but basically, 
the standard USB port specification doesn't meet the requirement for 
charging high-powered devices.  You may get some low level of charging if 
you connect to your PC's USB port with your iPad device turned off, and no 
other USB peripherals connected.  Recent Macs are built to supply more power 
through the USB ports if iOS devices with higher power requirements are 
connected, but that assumes that you don't have large numbers of other 
peripherals also powered from these ports.


HTH.  Cheers,

Esther


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USB ports on recent Macs can supply more than the USB standard power [was Re: IPad isn't charging: what the heck!]

2012-11-09 Thread Esther 
Hi Chris,

You wrote:

• So I wonder then why the macbook would charge it but not any windows machine? 
 Do macs tend to put out more vultage on their u s b ports?  Wonder what the 
amount of ampiers is it outputs.

The answer is that the standard USB port specification doesn't provide enough 
power to charge iPads.  That's one of the reasons that all the early 
generations of iPods (way back before the iPhone or iPod Nanos) used FireWire 
connectors.  But they moved to USB connectors when iPods became popular on PCs, 
and the lower power draw of these devices made that possible.

Recent model Macs are designed to detect when iPods and iOS devices are 
connected that require more power draw to charge than the default USB standard 
adopted by most PCs.  Depending on the load of what else you have plugged in, 
they will attempt to provide it.  Macs made before 2007 do not have this 
capability.  Here's a quote excerpted from an iLounge article:
• "Charging your iOS Devices on a Mac or PC" by Charles Starrett, September 1, 
2011
http://www.ilounge.com/index.php/tips/comments/charging-your-ios-devices-on-a-mac-or-pc/


On Macs newer than 2007, all your USB ports should supply at least 1100 mA of 
charging power to any device—such as an iPhone or iPad—that needs it. The extra 
power is doled out on a first come, first served basis, so the first device you 
plug in is virtually guaranteed to receive the maximum amount of power, while 
later devices are less likely. If you have a Mac that was built this year, it 
might even support full 2.1 Amp fast charging of the iPad. Mac users also have 
a very simple way to check how much juice each device is receiving. Simply go 
the the Apple menu, select About This Mac, and hit the More Info… button, which 
launches System Profiler. From there you can select USB from the sidebar under 
Hardware, and select the device you want to check on. It’ll show you the 
Current Available, the Current Required, and the Extra Operating Current—by 
adding the Available and Extra Current together, you’ll get the current power 
output for that port. For more info, see:
http://support.apple.com/kb/HT4049


The Apple Support document provides more specific details, but basically, the 
standard USB port specification doesn't meet the requirement for charging 
high-powered devices.  You may get some low level of charging if you connect to 
your PC's USB port with your iPad device turned off, and no other USB 
peripherals connected.  Recent Macs are built to supply more power through the 
USB ports if iOS devices with higher power requirements are connected, but that 
assumes that you don't have large numbers of other peripherals also powered 
from these ports.

HTH.  Cheers,

Esther  
 

<--- Mac Access At Mac Access Dot Net --->

To reply to this post, please address your message to mac-access@mac-access.net

You can find an archive of all messages postedto the Mac-Access forum at 
either the list's own dedicated web archive:

or at the public Mail Archive:
.
Subscribe to the list's RSS feed from:


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worm-free!

Please remember to update your membership options periodically by visiting the 
list website at: