If there's 10W of power through the Thunderbolt cable, why does it require an external power supply?

This drive shouldn't require any more than my Seagate 1TB HD, which is powered via either the Firewire cable or the USB cable. The whole idea is for this thing to be portable. Who wants to drag around a power brick? Was it because there was a push to deliver Thunderbolt peripherals, and the engineers skimped on the push to deliver everything via Thunderbolt? The whole idea of Thunderbolt was that you could get video, audio, data and power all through one cable. What's up?

LaCie Little Big Disk Thunderbolt Series Hard Drive

LaCie Little Big Disk Thunderbolt Series Hard Drive

Product No Longer Available

1 Answer from the Community

  • Answer

    You are right, there is indeed around 10W of power though the Thunderbolt port. However, the Thunderbolt cable is an active cable with some circuitry inside that already requires 5W. Then, you need to bare in mind that the Little Big Disk Thunderbolt Series embeds 2 internal hard drives. Therefore twice the power is required compare to a single external hard drive. Finally the Thunderbolt interface embedded in the product also requires a lot of power.
    All in all, despite the 10W of the Thunderbolt interface, it is not enough to bus power a multiple hard drives storage device like the Little Big Disk Thunderbolt Series. But this could be an option for future external storage with a single drive inside.