Are there any hard drive enclosures for 3.5" form HDs that can be powered off a USB port alone?
October 17, 2009 10:30 PM
Are there any hard drive enclosures for 3.5" form HDs that can be powered off a USB port alone? (ie, without additional AC plug)
I'm looking for a HD enclosure to use with a Western Digital 1.5 TB Caviar Green SATA Hard Drive (WD15EADS) that wouldn't require me to plug an AC adapter into the wall. WD claims this drive uses 40% less power -- not sure if that matters.
It will be primarily connected to a MacBook (5.1) that has 2 USB 2.0 ports, but no FireWire.
I'm looking for a HD enclosure to use with a Western Digital 1.5 TB Caviar Green SATA Hard Drive (WD15EADS) that wouldn't require me to plug an AC adapter into the wall. WD claims this drive uses 40% less power -- not sure if that matters.
It will be primarily connected to a MacBook (5.1) that has 2 USB 2.0 ports, but no FireWire.
No, because USB ports are limited to 500ma, though some non-standard motherboards and laptops will provide up to 750ma. You can use 500GB 2.5" laptop drives in external enclosures without any problem.
posted by thewalrus at 11:03 PM on October 17, 2009
posted by thewalrus at 11:03 PM on October 17, 2009
There do exist USB HD drives which run off the USB power, but those use specially-chosen HD's which use considerably less power than normal.
Actually, many of the bus-powered USB HDDs I've seen don't do that. This is why they're often shitty. I'm not a fan of powering a hard drive from USB alone-- I've never seen it done elegantly, and they tend to be flaky at the worst times, randomly incompatible with motherboards that conform strictly to USB spec, etc.
Bus-powered 3.5" cases? I've never seen a FireWire case like that, let alone USB. I'd be surprised.
posted by aaronbeekay at 11:29 PM on October 17, 2009
Actually, many of the bus-powered USB HDDs I've seen don't do that. This is why they're often shitty. I'm not a fan of powering a hard drive from USB alone-- I've never seen it done elegantly, and they tend to be flaky at the worst times, randomly incompatible with motherboards that conform strictly to USB spec, etc.
Bus-powered 3.5" cases? I've never seen a FireWire case like that, let alone USB. I'd be surprised.
posted by aaronbeekay at 11:29 PM on October 17, 2009
I had a 2.5" enclosure that ran off the bus... but, I've never seen a 3.5" one. For current-draw reasons people have explained above.
posted by Netzapper at 11:50 PM on October 17, 2009
posted by Netzapper at 11:50 PM on October 17, 2009
There are/have-been Bus-powered 3.5" enclosures available (most notably, the now discontinued Wiebetech UltraGB+), but to my knowledge they have been limited to Firewire bus-power (due to the inherent power limitations of USB), and to 3.5" IDE drives, not SATA.
Wiebetech has a whitepaper that explains the pitfalls and caveats with running bus-powered 3.5" drive enclosures. Reading the whitepaper will almost certainly turn you off from considering this idea any further. It also probably explains why Wiebetech no longer sells this product, because it's way more trouble than it's worth.
Other World Computing now sells their extremely popular Mercury On-the-Go 2.5" enclosure in a 1TB configuration. It's $300 for a USB2-only interface, but you're not going to find any other single-enclosure bus-powered solution for any cheaper.
posted by melorama at 8:13 AM on October 18, 2009
Wiebetech has a whitepaper that explains the pitfalls and caveats with running bus-powered 3.5" drive enclosures. Reading the whitepaper will almost certainly turn you off from considering this idea any further. It also probably explains why Wiebetech no longer sells this product, because it's way more trouble than it's worth.
Other World Computing now sells their extremely popular Mercury On-the-Go 2.5" enclosure in a 1TB configuration. It's $300 for a USB2-only interface, but you're not going to find any other single-enclosure bus-powered solution for any cheaper.
posted by melorama at 8:13 AM on October 18, 2009
Two solutions:
(1) replace your current internal disk with a larger one; or
(2) use or install a PC Card port and a PC Card disk.
Number 1 is better, because it's a direct motherboard connection without the overhead of the PC Card.
posted by KRS at 9:08 AM on October 18, 2009
(1) replace your current internal disk with a larger one; or
(2) use or install a PC Card port and a PC Card disk.
Number 1 is better, because it's a direct motherboard connection without the overhead of the PC Card.
posted by KRS at 9:08 AM on October 18, 2009
You'll never find a USB bus-powered 3.5" drive.
Even the WD Green series of 3.5" drives require 5.4 watts while reading/writing. 5.4 watts at 5 volts is about 1 amp. You can only guarantee .1 amp is available from any one USB port, and .5 amp from a USB root hub on the motherboard.
It would take the power of 2 or 3 USB ports, dedicated to the task, to drive a WD Green drive. WD Green datasheets
posted by Rendus at 9:11 AM on October 18, 2009
Even the WD Green series of 3.5" drives require 5.4 watts while reading/writing. 5.4 watts at 5 volts is about 1 amp. You can only guarantee .1 amp is available from any one USB port, and .5 amp from a USB root hub on the motherboard.
It would take the power of 2 or 3 USB ports, dedicated to the task, to drive a WD Green drive. WD Green datasheets
posted by Rendus at 9:11 AM on October 18, 2009
3.5 inch drives with a special USB cable that forks into two sockets are available. I would guess that if you can source the cable alone that would do you. I have one and it works just fine.
posted by fingerbang at 1:34 PM on October 18, 2009
posted by fingerbang at 1:34 PM on October 18, 2009
I think fingerbang is confusing 3.5inch with 2.5inch, as there are many USB drives in the laptop 2.5 form factor, but the spec of 3.5" drives precludes USB bus power, as other mentioned above.
posted by bystander at 3:53 AM on October 19, 2009
posted by bystander at 3:53 AM on October 19, 2009
This thread is closed to new comments.
USB is limited to half an amp of 5 volts, or 2.5 watts. Your preferred drive dissipates 3.7 watts idle, and 6 watts when reading or writing.
posted by Chocolate Pickle at 10:55 PM on October 17, 2009