Thursday, June 25, 2009

IPhone charging from a laptop - changes for the better?

I first blogged about charging my cellphone from a laptop back in 2004 (Palm too). Later I charged my iPod as well. It's worked reasonably well over the years, but recently things have changed for the better.

I used to plug my iPods and iPhones into my corporate XP laptop when they needed a charge at the office. Back in the day I had to install iTunes associated device drivers to get the laptop to power the USB port, and that meant iTunes was prone to try to seize control of the iPod.

That's bad enough, but now our corporate XP boxes are so fragile I'm grateful to get through the day without a new IT disaster. I don't dare add something as potentially disruptive as iTunes to the witches brew of antivirus, configuration management, surveillance, encryption, firewall and antimatter that infests our laptops. (It takes two cores just to run the security layers.)

So when my iPhone faded on a plane flight, I didn't have much hope. Still, I connected it.

Yes, it charged. Not only did it charge, but it charged faster than with a conventional USB charger -- even before I put it in airplane mode. I've read that modern laptops deliver much more current than the USB spec suggests, so maybe I wasn't imaging things.

I don't really know what's changed. Maybe the iPhone was always able to register as a camera and thus engage the USB port's power. Maybe iPhone OS 3 makes the difference. Maybe it's the new laptop, perhaps USB ports now provide power even without a device driver request.

Whatever, it works. So it you haven't tried charging your iPhone from your corporate laptop, give it a try. It might just get you through a day of heavy iPhone use.


  1. Typically, USB ports always supply power... its part of the specs. Granted, some computers/laptops may deliver more juice (watts) for charging faster.

    I've never heard of having to engage camera mode or something like that to have the USB port deliver power... FYI

  2. I have a weird memory that the ports used to need some kind of request to provide USB 2 power, that the default used to be USB 1.

    I do remember needing to install device drivers to get power to some of my devices. For example, to get my Mac laptop to power my Motorola RAZR I had to install a simple device driver Scott Gruby put together:

    I couldn't find a Google reference to this behavior however. Maybe it was OS X only?

  3. i have 3 chargers exploded...tried it on laptop and it works well..and jgf youre right, it register as a camera...options with picasa etc...i just click the close icon