3.5" USB HDD Enclosure - USB Powered?

[spoon_]

Do they even exist?

[b0redom]

Never seen one. I believe that the reason is that the drives require more power than a USB port can deliver.

[Ferral]

Yes, you can get them. I need one for my old 60Gb IDE drive as the main system went pop due to water. I came across this :

http://www.amazon.co.uk/Hard-Drive-C.../dp/B002K00G0W

You can get them for SATA drives also

There is also a decent site called USB Now :

http://www.usbnow.co.uk/Hard_Drive_E...c10/index.html

[b0redom]

That's not USB powered.

[Ferral]

Yeah, youre right, didnt notice at time of posting. I know you used to be able to get them, but there were problems due to the low power on the USB ports (500ma max believe).

I think you can still get Firewire ones but they could be hard to come by.

Most solutions now do require an external power source unfortunately.

[killie99]

I'd be amazed if you can get a USB powered 3.5" caddy as a 3.5" disk needs about 2A at startup and that will potentially fry your motherboard if you try and pull that sort of current from a USB port.

[spoon_]

Gigabyte and others with on/off charge for iPads/iPhones are able to provide almost 1A through USB port so I don't think we are that far off...

http://www.youtube.com/watch?v=_tIttqI_pdM

USB ports conforming to Battery Charging v1.2 standard can push 1.5A down the USB wire.

USB3 can do .9A out of the box [but I need enclosure to comply with 2.0]

[this_is_gav]

USB powered 2.5" disks are actually very close to the line in terms of power (hence why IcyBox provide 2 USB cables with their 2.5" enclosures, which join together). In my experience the real limit is the length of cable, as the power drop dramatically the longer the cable.

Given that 2.5" drives are so tight, a 3.5" drive will probably never exist with the current standards.

[watercooled]

Another electrical problem is 3.5" drives need 12v as well as 5v which USB supplies, 2.5" drives generally only need 5v. This would add the need for another power supply, drawing more current. Spin-up current would be a major problem for a 3.5" drive, as above - even low-speed drives draw 1.5-2A on the 12v rail alone, plus another amp or so on 5v, combined they go way over what USB can supply.

[micre23]

Another electrical problem is 3.5" drives need 12v as well as 5v which USB supplies, 2.5" drives generally only need 5v. This would add the need for another power supply, drawing more current. Spin-up current would be a major problem for a 3.5" drive, as above - even low-speed drives draw 1.5-2A on the 12v rail alone, plus another amp or so on 5v, combined they go way over what USB can supply.

They do exist, here is a example.
[This model supports up to 3TB]

[Agent]

USB powered 2.5" disks are actually very close to the line in terms of power (hence why IcyBox provide 2 USB cables with their 2.5" enclosures, which join together). In my experience the real limit is the length of cable, as the power drop dramatically the longer the cable.

I've found the quality of the cable makes a huge difference. I've some shorter, thin ones that can't power a single drive. Some of the longer, thicker ones are fine though. But yeah, length is always going to matter

[peterb]

And I think they existed three years ago when the OP first asked the question!

But yeah, length is always going to matter

Very sigworthy!

[watercooled]

They do exist, here is a example.
[This model supports up to 3TB]

I'd be surprised if they adhered to the USB spec though. I wasn't claiming 12v couldn't be derived from 5v, but you'd be pulling a *lot* more current than USB is designed to provide, which at best might work without problem on some computers, or it might cause the drive to fail to spin up and make weird sounds, or worse might trip the PSU, resetting the computer or possibly even damage something.

[micre23]

I'd be surprised if they adhered to the USB spec though. I wasn't claiming 12v couldn't be derived from 5v, but you'd be pulling a *lot* more current than USB is designed to provide, which at best might work without problem on some computers, or it might cause the drive to fail to spin up and make weird sounds, or worse might trip the PSU, resetting the computer or possibly even damage something.

Well, I haven't had any of those problems with it. The workaround they use is by putting a battery inside the enclosure.

[watercooled]

The battery could certainly help with the spin-up surge, but even so you're going to be dangerously close to, and most likely breaching, the USB spec. The USB3.0 spec states devices which are not charge-only, may pull up to 0.9A at 5V. This is 4.5 watts. Of course there will be losses in the boost converter turning that to 12v but even ignoring them, 3.5" drives tend to pull 3-5+ watts when idle, let alone the active power.

Indeed, breaching the spec may not cause issues in many cases, but the potential is there, which is precisely the reason we don't see anything besides no-name devices where there is essentially no-one to hold liable when something gets destroyed, and why reputable manufacturers won't touch them with a bargepole.

[micre23]

The battery could certainly help with the spin-up surge, but even so you're going to be dangerously close to, and most likely breaching, the USB spec. The USB3.0 spec states devices which are not charge-only, may pull up to 0.9A at 5V. This is 4.5 watts. Of course there will be losses in the buck converter turning that to 12v but even ignoring them, 3.5" drives tend to pull 3-5+ watts when idle, let alone the active power.

Indeed, breaching the spec may not cause issues in many cases, but the potential is there, which is precisely the reason we don't see anything besides no-name devices where there is essentially no-one to hold liable when something gets destroyed, and why reputable manufacturers won't touch them with a bargepole.

Fair point, but it has worked well for me.

Here is a clip showing it in use, please excuse the poor video quality