Back-UPS garbage? (was: Quick survey -- UPSs on slave nodes?)

Jim Lux James.P.Lux at
Mon Feb 10 17:36:19 PST 2003

All a matter of carefully reading the specs..

The run of the mill APC unit Back-UPS CS 350VA, for instance, specs a hold 
up time of only 4.7 minutes at full load (210 Watts).. gets a lot better at 
half load (105W) for 18.1 minutes. However, given that the run of the mill 
monitor and PC probably draw close to 200-300W, that "350VA" UPS isn't 
going to cut it.

The smallish units work quite nicely to, for instance, allow a DSL 
modem/firewall/hub to ride through a short outage.

One has to wonder, though, if they are getting perilously close to "puffing"...

The Back-UPS VS 500 Broadband, intended to protect the desktop machine, 
monitor, broadband hookup, etc.... 325W rated output (500VA) only has a 2.8 
minute(!) runtime... better be hot stuff on the keyboard and mouse to get 
shut down quickly..

"The APC Back-UPS VS provides a complete solution for home networking needs 
by protecting your high-speed Internet lines (telephone, coaxial cable and 
ethernet) from surges, by providing battery backup for your desktop, 
monitor, hubs and routers in case of power failure and surge protection for 
up to 3 other non-data peripherals such as printers and scanners."

Let's see, based on the back panel markings...
A Dell M770mm 17" monitor is 1.1A @ 120V.. 144VA (probably pretty close to 
1.0 pf, so figure 144W, too)
A Compaq E600 1.6GHz P4 stickered at 3.6A@ 120V 432VA... Let's be generous 
and allow them 80% power factor, 350W, just there...

oops, we're already over the 500 VA limit...

At 05:18 PM 2/10/2003 -0600, you wrote:
><alvin at> writes:
> > $40 el cheapo APC for each node...
>I assume you're referring to the ``Back-UPS'' line.  The only thing
>I've found those to be able to support on battery power is my clock
>radio, which I could more easily protect with a 9-volt.
>Has any one of you actually used these to sustain a PC for any
>measurable length of time?  I'm not sure at what market this junk
>is aimed, perhaps suckers.
>Beowulf mailing list, Beowulf at
>To change your subscription (digest mode or unsubscribe) visit 

James Lux, P.E.
Spacecraft Telecommunications Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
tel: (818)354-2075
fax: (818)393-6875

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