USB bus power limit for HD

[Clive]

I currently have 3 2.5" USB external drives (all under 160gb). I use one
for a bootable backup, one to back up my data and one for my pictures
(I'm Wedding photographer).

As the drives are physically small and run directly off the USB bus off
my Mac, I can take them all to shoots. The problem is the size is now
becoming too small and I am looking at something of 500gb upwards.

I generally power my Mac, Camera chargers from an inverter in my car, so
a drive without an additional power supply would be ideal.

Are there any drives of this size that can be powered directly from the
USB bus?

Thanks

 

[Arno Wagner]

I currently have 3 2.5" USB external drives (all under 160gb). I use one
for a bootable backup, one to back up my data and one for my pictures
(I'm Wedding photographer).

As the drives are physically small and run directly off the USB bus off
my Mac, I can take them all to shoots. The problem is the size is now
becoming too small and I am looking at something of 500gb upwards.

I generally power my Mac, Camera chargers from an inverter in my car, so
a drive without an additional power supply would be ideal.

Are there any drives of this size that can be powered directly from the
USB bus?

No. The USB bus can (at a high-power port) supply 0.5A. That is
2.5W, barely enough for a notebook HDD. The largest notebook
HDDs on the market are 200GB. For a 3.5" 500GB HDD, you need to
provide about 30W of AC. On the other hand, notebook HDDs are far
more rugged and more likely to survive a (short) fall, so you may
want to go with several 2.5" notebook HDDs.

Arno