Tiny Uninterruptible Power Supply for 3.5" External HDD? Does a product exist? - Page 1
Forum section: electronics / general

author: salil
author_rank: Regular Contributor
timestamp: June 24, 2014, 10:30:58 pm
content: I frequently find myself in a situation where I need to move a laptop connected to a 3.5" external hard drive to a wall outlet in a different room, but I've got an encoding job going or am uploading some large files, so I can't eject the external drive without interrupting the job(s). It seems like most people who find themselves in this sort of situation and actually care are using bus powered drives these days but I need to use 3.5" drives for a variety of reasons.I haven't been able to find any product designed for this sort of low power and frequent short usage time, does anyone know if a product like this exists?All I need is a small uninterruptible power supply that can power a 12v DC ~1A external hard drive (all my drives use a 2.1mm dc barrel connector like they use for CCTV systems) for 5 minutes or so (and also charges automatically while plugged into a 120v AC wall outlet like most full size UPS's do in the USA). Sure, I could use the smallest regular computer UPS I can find, but it's unnecessarily large and not the most efficient solution since I'm going from AC>DC>AC>DC. Any ideas?

author: jeremy
author_rank: Super Contributor
timestamp: June 24, 2014, 10:42:31 pm
content: A small lead acid battery?But to be honest, I think problem will be that the 3.5 inch drive will not be very happy being moved. They aren't designed for that.

author: Mr.B
author_rank: Unknown
timestamp: June 24, 2014, 10:49:07 pm
content: I have used 'PicoUPS' in the past.Not for the same application as you, but for 12v UPS requirements.http://www.mini-box.com/picoUPS-100-12V-DC-micro-UPS-system-battery-backup-system

author: sleemanj
author_rank: Super Contributor
timestamp: June 24, 2014, 10:50:34 pm
content: I'd diy it.18650 cell or 2 in parallel, pref protected onesTP4056/7 charger moduleBoost or sepic converter to get the 12v when on cell supplyCouple of diodes to OR between having cell supplying converter or wall supplying converterSuitable plugSent from my HTC Dream using Tapatalk 2

author: denelec
author_rank: Regular Contributor
timestamp: June 25, 2014, 12:43:59 am
content: Quote from: jeremy on June 24, 2014, 10:42:31 pmHe's right.A small shock on the disk drive while it's spinning could crash the heads on the platters.When the hard drive is off, the heads are parked and much more resistant to shock.Laptop hard drives are more resistant to shock than 3.5 inch ones.

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: June 25, 2014, 02:45:12 am
content: sounds like a NAS would be better , and connect that to a UPS .

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 26, 2014, 04:02:05 am
content: Belkin makes a 12V mini UPS for this sort of application. Not sure where to buy them. DIYing one shouldn't be too difficult.

author: macboy
author_rank: Super Contributor
timestamp: June 27, 2014, 03:30:36 pm
content: Quote from: salil on June 24, 2014, 10:30:58 pmYou are worried about efficiency in a system that will run for a couple minutes at a time, every few days?Be more worried about the integrity of your data on a 3.5" drive that's being jostled around. Ouch. Unlike laptop drives, these are NOT meant to be moved. The platters are bigger, more numerous, and spin faster. You would not believe the gyroscopic forces applied to the bearings in that drive if you twist it even a little. They don't have the same motion sensors and automatic head parking that laptop drives have, to prevent the heads from plowing into the disk surface when jostled.I suggest that if you must have mobility, and you must use 3.5" drives, then you might consider connecting the drives to a NAS server so that the drive doesn't need to move when you do. If that isn't OK, then you need to re-consider either the mobility part, or the 3.5" part, because those two things do not jive.

author: nowlan
author_rank: Frequent Contributor
timestamp: June 29, 2014, 02:29:15 pm
content: Would this work for you?http://www.dx.com/p/ysd-12450-12v-4500ma-rechargeable-lithium-battery-80405

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 29, 2014, 02:38:38 pm
content: Would your job not tolerate going to hibernate/standby etc. for the duration?

author: amyk
author_rank: Super Contributor
timestamp: June 30, 2014, 12:06:43 pm
content: +1 to the worry about the HDD. Damage may not show up immediately because they do things like sector remapping and read/write retries but eventually that doesn't help anymore and you start losing data.(2.5" drives are not shock-resistant either, but may tolerate movement quite a bit more.)