Thoughts on using a USB disk on a cheapo UPS?

I don't have a high opinion of an external USB disk powered by a
wall-wart as industrial-strength kit. Having the PC powered on a UPS
and the Wall wart on house power has potential problems, IMO.

What are the thoughts of putting retail external USB disks on
entry-level UPS systems? These systems are stepped-sine power and
they don't specify switch-over time.

??


--
Al Dykes
News is something someone wants to suppress, everything else is advertising.
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Al Dykes wrote:
I don't have a high opinion of an external USB disk powered by a
wall-wart as industrial-strength kit. Having the PC powered on a UPS
and the Wall wart on house power has potential problems, IMO.

What are the thoughts of putting retail external USB disks on
entry-level UPS systems? These systems are stepped-sine power and
they don't specify switch-over time.

I've always found UPS's have a life of less than 3 years.

Yousuf Khan

Al Dykes wrote:

I don't have a high opinion of an external USB disk powered by a
wall-wart as industrial-strength kit. Having the PC powered on a UPS
and the Wall wart on house power has potential problems, IMO.

The wall-type PSUs are electrically insulated, there should not
be a problem, except perhaps aestetically.

What are the thoughts of putting retail external USB disks on
entry-level UPS systems? These systems are stepped-sine power and
they don't specify switch-over time.

To what end? It should work, but it only makes sense if you
have the PC on an UPS as well. Also take care to use the
VA rating (V * A as stated on the plug), as switching power
plugs may not have power factor correction.

Personally I have my external USB disks on the PCs
12V power rail, but that takes decoupling (I use
a pair of STPS 3045 for that) and dampening (0.2R or
so, but a 4A fast-acting fuse also dampens enough
for two disks).

Arno
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Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans

In article , Arno wrote:
Al Dykes wrote:

I don't have a high opinion of an external USB disk powered by a
wall-wart as industrial-strength kit. Having the PC powered on a UPS
and the Wall wart on house power has potential problems, IMO.

The wall-type PSUs are electrically insulated, there should not
be a problem, except perhaps aestetically.

They are also made by the lowest bidder. Of course, plugging one into
a UPS doesn't change that.


What are the thoughts of putting retail external USB disks on
entry-level UPS systems? These systems are stepped-sine power and
they don't specify switch-over time.

To what end? It should work, but it only makes sense if you
have the PC on an UPS as well. Also take care to use the
VA rating (V * A as stated on the plug), as switching power
plugs may not have power factor correction.


Voltage differentials, ground loops?

--
Al Dykes
News is something someone wants to suppress, everything else is advertising.
- Lord Northcliffe, publisher of the Daily Mail

Al Dykes wrote:

I don't have a high opinion of an external USB disk powered by a
wall-wart as industrial-strength kit. Having the PC powered on a UPS
and the Wall wart on house power has potential problems, IMO.

What are the thoughts of putting retail external USB disks on
entry-level UPS systems? These systems are stepped-sine power

Thats irrelevant. They all rectify the mains, none use the mains directly.

and they don't specify switch-over time.

I prefer always on/continuous UPSs myself.

They dont necessarily cost anymore now.

Al Dykes wrote:
In article , Arno wrote:
Al Dykes wrote:

I don't have a high opinion of an external USB disk powered by a
wall-wart as industrial-strength kit. Having the PC powered on a UPS
and the Wall wart on house power has potential problems, IMO.

The wall-type PSUs are electrically insulated, there should not
be a problem, except perhaps aestetically.

They are also made by the lowest bidder. Of course, plugging one into
a UPS doesn't change that.

Yes. But the insulation requirement ensures that you do not get
ground loops or current over ground.

What are the thoughts of putting retail external USB disks on
entry-level UPS systems? These systems are stepped-sine power and
they don't specify switch-over time.

To what end? It should work, but it only makes sense if you
have the PC on an UPS as well. Also take care to use the
VA rating (V * A as stated on the plug), as switching power
plugs may not have power factor correction.

Voltage differentials, ground loops?

No ground loops with the standard wall plugs. Voltage differential
is not a problem with wide-input ones. With heavy transformer types
it should not be an issue either, but they are less resilient.

Arno
--
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email:
GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
----
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans

On 4/9/2010 8:24 AM, Yousuf Khan wrote:

I've always found UPS's have a life of less than 3 years.

My APC 350 and 700 have gone way past where they wanted me to replace
the batteries.

I always run my external HD off the 700.

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Hi!

I don't have a high opinion of an external USB disk powered by a
wall-wart as industrial-strength kit. Having the PC powered on a UPS
and the Wall wart on house power has potential problems, IMO.

The included power supplies are almost invariably the switchmode type. Some
put out both voltages required by the drive and bridge board (5V/12V) while
others only put out straight +12VDC and let a DC-DC converter in the
enclosure produce +5VDC.

The wall wart is almost always a switchmode power supply--cheap,
lightweight, easily able to handle wide ranges of input voltages and
reliable if properly made. Most seem to output about 2 amps, and good ones
don't get all that hot (suggesting that they ought to live a long time).

What are the thoughts of putting retail external USB disks on
entry-level UPS systems? These systems are stepped-sine power and
they don't specify switch-over time.

I've had no problems. I have a setup with the disks on one UPS and the
computer on another. Both UPS units are cheap APC "plugstrips", each one
about five years old. One is on its second battery. Both are plugged into
the same duplex outlet, on the same circuit.

William