USB port powerful enough to power a external USB drive?

[NRose8989]

I was wondering if the since the MBA's USB port has extra power running through it, if it is able to power a USB drive without a AC adapter.

 

[dborja]

I was wondering if the since the MBA's USB port has extra power running through it, if it is able to power a USB drive without a AC adapter.

Yes. I've used it with a Seagate FreeAgent Go for backups and Time Machine with no problems.

 

[SFStateStudent]

+1 ^^^ No problem whatsoever. If it can handle your MBAir Superdrive, it can definitely handle the external USB drive...

 

[millar876]

only issue you might have is some 2.5" HDD cases require 2 USB Ports to power them, and cos the MBA only has 1, you'd need to use a hub, which might not pull through enough power from the port as its a non standard (as far as power output goes) USB port

 

[dborja]

only issue you might have is some 2.5" HDD cases require 2 USB Ports to power them, and cos the MBA only has 1, you'd need to use a hub, which might not pull through enough power from the port as its a non standard (as far as power output goes) USB port

That's true. If you buy an external 2.5" drive, as opposed to building one, it usually is of the single port variety so I'd stick with those. Prices are better nowadays for external drives than for DIY external drives. So unless you absolutely want a specific drive or already have one...

 

[johnnj]

I'm using a WD 320 gb 7200rpm drive in a cheap NexStar enclosure. It came with one of those two port USB cables, but the drive works just fine on the MBA's port using a normal cable.

 

[hodgeheg]

Basically, Yes.

Many external drives come with a two port cable. This is for use on computers that don't supply quite enough power over a USB port. I've never needed to actually use the second one with any Mac (and I've had a lot, believe me), and the Air (which I now have) has a higher powered USB port than just about anything.

I use an external case that contains my old MacBook's hard drive. For neatness I replaced the 2 plug cable with a single plug cable. It works fine.

 

[n8236]

If memory serves me right, the total amount of power of all the USB ports on most laptops is 500mA. Do not confuse this as each USB port having 500mA. So, depending on the # of USB ports available, the 500mA gets distributed among them accordingly.

Also, if you're plugging in an USB device that requires a substantial amount of power (ie. ext 2.5" hd), make sure you use the thicker cables. The thin ones only provide data transfer (for the most part).

 

[illegallydead]

If memory serves me right, the total amount of power of all the USB ports on most laptops is 500mA. Do not confuse this as each USB port having 500mA. So, depending on the # of USB ports available, the 500mA gets distributed among them accordingly.
Also, if you're plugging in an USB device that requires a substantial amount of power (ie. ext 2.5" hd), make sure you use the thicker cables. The thin ones only provide data transfer (for the most part).

The USB port on the MBA is actually over-powered from the official USB spec. (more or less specifically because of the SuperDrive accessory)

So yes, it will have plenty of power. If it has enough juice to spin a big 'ol CD around off of just USB, than it has plenty to power the little platters of an HDD (especially newer ones, as they are getting more and more power efficient).

only issue you might have is some 2.5" HDD cases require 2 USB Ports to power them, and cos the MBA only has 1, you'd need to use a hub, which might not pull through enough power from the port as its a non standard (as far as power output goes) USB port

Those cables that have a split are only if you need the extra juice, which is really only a problem on older laptops and some un-powered USB hubs (I say some because I had a cheap-o one from Wal-Mart for YEARS that would power anything and everything I put in it, and that was w/o any form of extra power adapter )