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07-30-2011

Australia

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iPad stops charging when I turn on Thinkpad (not iPad!!!)

2011-07-30, 1:19 AM

Hi

I am aware that the iPad requires more power than traditional USB devices. So it does not charge on every USB port but only on some.

When I plug my iPad into the USB port of my new T420s it charges (i.e. the port is a high powered port capable of charging the iPad) if, but only if the laptop it turned off.

When I turn on the laptop the USB port switches into a lower power mode that can not charge the iPad and charging stops.

 

Is there a special driver I need to install to allow the port keep it's high power state when the laptop is turned on?

Mark

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5371 Posts

04-25-2008

United States of America

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Re: iPad stops charging when I turn on Thinkpad (not iPad!!!)

2011-07-30, 5:26 AM

Hi mschira, and welcome to the Lenovo User Community!

 

I did some testing a while ago with the yellow always-on USB port on my X220, and discovered that even though my iPad says "Not Charging", it is actually charging slowly, but not as fast as when the ThinkPad is off (and the iPad shows that it is charging). I haven't found a way to change this behavior.

 

 

USB-C: Just cos it fits don't mean it works.
I don't work for Lenovo. I'm a crazy volunteer!
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21115 Posts

12-20-2008

Australia, Melbourne

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Re: iPad stops charging when I turn on Thinkpad (not iPad!!!)

2011-07-30, 6:27 AM
the full 10 watt of power is only supplied when the laptop is off. It is a hardware feature AFAIK.
Regards,

Jin Li

May this year, be the year of 'DO'!

I am a volunteer, and not a paid staff of Lenovo or Microsoft
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7 Posts

07-30-2011

Australia

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Re: iPad stops charging when I turn on Thinkpad (not iPad!!!)

2011-08-01, 10:09 AM

@lead_org

Well it certainly seems so that the 10W power is only available when the Thinkpad is turned off.

Weird. Anoying. I would understand if it is only available when the laptop is plugged in (versus battery)- but that's actually not the case.

 

And yes it kinda charges the iPad - but only very very slowly (like 2 days or so) and only when the iPad is in standby.

When the laptop is turned off it charges the iPad much much faster.

M.

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9644 Posts

12-27-2009

Canada

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Re: iPad stops charging when I turn on Thinkpad (not iPad!!!)

2011-08-01, 10:42 AM
10W is a non-standard amount of power to be supplied through a USB port. It's possible that the BIOS prevents this from happening while powered on to avoid confusing a host OS driver.

W520: 2960XM, Q2000M @ 1091/1380, 32GB RAM, 500GB&750GB HDD & 500GB SSD, FHD&MB168B+
X61T: L7500, 4GB RAM, 500GB HDD, XGA screen, Ultrabase
W550s: 5600U, K620M at 1164/1281, 16GB RAM, 512GB SSD, 3K touchscreen
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TPT1: 1839-23U
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21115 Posts

12-20-2008

Australia, Melbourne

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Re: iPad stops charging when I turn on Thinkpad (not iPad!!!)

2011-08-01, 11:35 AM
There are not many usb ports that can supply 10 watts of power when they are fully operational and transferring data. Not sure why that is case, but it could be that the usb implementers forum never really approve such design (my guess only).

Anyway, i just charge my iPad with the 10 watt adapter.
Regards,

Jin Li

May this year, be the year of 'DO'!

I am a volunteer, and not a paid staff of Lenovo or Microsoft
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63 Posts

10-24-2010

United States of America

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Re: iPad stops charging when I turn on Thinkpad (not iPad!!!)

2011-08-01, 14:28 PM

ColonelONeill,

Do you happen to know that the standard amount of power for a USB port?

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9644 Posts

12-27-2009

Canada

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Re: iPad stops charging when I turn on Thinkpad (not iPad!!!)

2011-08-01, 15:11 PM
http://en.wikipedia.org/wiki/Usb#Power

5V.

W520: 2960XM, Q2000M @ 1091/1380, 32GB RAM, 500GB&750GB HDD & 500GB SSD, FHD&MB168B+
X61T: L7500, 4GB RAM, 500GB HDD, XGA screen, Ultrabase
W550s: 5600U, K620M at 1164/1281, 16GB RAM, 512GB SSD, 3K touchscreen
X200s: SL9400, 6GB RAM, 64GB SD card, WXGA+ screen
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63 Posts

10-24-2010

United States of America

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Re: iPad stops charging when I turn on Thinkpad (not iPad!!!)

2011-08-01, 15:30 PM

Ok, 5 Volts mutiplied by 500 mA (0.5 A) equals 10 Watts. If no data transfer, there should be 10 W on the port then.

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21115 Posts

12-20-2008

Australia, Melbourne

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Re: iPad stops charging when I turn on Thinkpad (not iPad!!!)

2011-08-01, 15:42 PM
5 x 0.5 A = 10 Watts? (more like 2.5 watts)
Regards,

Jin Li

May this year, be the year of 'DO'!

I am a volunteer, and not a paid staff of Lenovo or Microsoft
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