For discussion of UPSes

21 responses total.

A Tripp-Lite BC-450 "Internet" failed while off but plugged in for a week.
The symptom is no response at all to "on" switch. An inspection of the
user unserviceable parts indicated that the power switch is OK. However
there is a plug onto the PCB with three wires from the x-former: all
pairs of those wires tested open with a VOM. This seems like an unlikely
failure as one would think that those three wires go to a center tapped
winding, and *two* should not fail together. (There was no sign of
overheating.) Any comments?

Also, the prime UPS makers seem to be APC and Tripp-Lite. Any comments on

APC UPS's seem to work fine, though the useful life of the batteries
isn't all that long.  I've seen anywhere from 2 to 4 years depending on
the temperature.  They also have one odd quirk -- the relay that engages
the charging circuit is powered by the battery.  If you let the UPS sit
unplugged long enough that the battery completely self discharges, the
UPS will be non-functional until you replace the battery, charge it
seperately, or 'jump-start' it off a good battery.  I've never seen this
happen except in units that were discharged and then left unplugged for
long periods of time, though, or that had suffered complete battery
failures.

APC also makes (or at least used to make) a couple different model
lines.  At work we have some Back-UPS units, and some Smart-UPS and
Back-UPS Pro units.  The Back-UPS line only has "simple signalling",
which means the computer can only tell if the power is on or off and
whether the battery is low.  There's no other monitoring capability, and
no self-test ability.  Smart-UPS and Back-UPS Pro models can report line
and battery voltages, percent load, and percent battery capacity to the
computer, and can also do regular self-tests and warn you when the
battery needs replacing.  That's probably overkill for home use, though.

Oh, one other comment.  At home I have a couple of CyberPower UPS units.
 These are cheap but I cannot recommend them.  They seem to flake out in
odd ways, and generally act unpredictably, which isn't a good thing in a
UPS.

I second those comments (except the very technical parts,
because I'm not THAT familiar with APS).

I do wish APC would leave a little room around their batteries.  They're
pretty tight fits, which is fine when they're new.  But when gel cell
batteries fail, they tend to swell, and in an APC UPS this often means
the battery is very firmly wedged in place when you need to replace it.

tsk

I'm looking for a small rack-mount UPS of about 1 to 1.5 kVA.
Its primary load will be an analogue PBX.  Any suggestions?

Check your PBX to see if it has a DC power option, first.  Some can run
off a bank of 12V batteries.  This would be more efficient and cheaper
than going through all the power conversion hardware of a UPS.

Re #8: That would certainly be nice, bypassing the the DC-AC
  invertor in the UPS and the AC-DC PSU in the switch (and
  the both the losses and potential points of failure
  involved in both of those stages).  Sadly I don't think
  that is an option on this AT&T/Lucent/Avaya Partner system
  (which somebody else specified and installed).

That could be, though it's unfortunate.

Years ago, phone systems used to run entirely off battery banks, and AC
power was only used to keep them charged.  Most railroad signals run
that way to this day.

Re #10: It makes a lot of sense.  I wonder if that's another
  of those ideas that will re-surface again in the future.

"Online" UPSs run entirely off their battery, with AC power keeping the
battery charged. 

Which bring up a possible problem I am having with a Tripp-Lite BC 
Internet 675 UPS (purchased in 1999). When there is a line power dip I 
hear a "click" and sometimes it is apparent that a power dip got through 
the UPS. My monitor screen may flicker, and sometimes the computer crashes 
(showing what I call the "grey screen of death" - it is a Mac with OS X). 
It is, however, one of what Tripp-Lite called their "BC Internet On-Line 
UPS Systems". I am wondering now whether they don't mean "On-Line" as I 
noted above (UPSs that run entirely off their batteries). If it is, what 
the the "click"?

Maybe the UPS batteries are shot and can't carry the load anymore. 
Eight years is a long time to ask a lead-acid battery to last -- I
usually only get four to five years out of UPS batteries.

I can turn off the power to the UPS and the transfer occurs without a 
problem and the battery certainly lasts many minutes when I have done that 
intentionally - all the time I need to shut down. But what would be the 
"click" I hear from the UPS when there are power dips? (I can't hear it 
when I switch off the power as the noise of doing that is louder than the 
UPS's click.) Do any true "on-line" UPSs exhibit a "click"? 

I think you were right, or prescient, David: my Tripp-Lite UPS has finally
just failed, suddenly shutting down the computer. It is not built for easy
battery replacement, so I've gotten a new APC. This works fine, confirming
that the problem I describe in #12 was the UPS. 

I'll be recycling a bad Tripp-Lite as a battery at the Drop-Off station -
unless someone has a use for any of its parts. I would probably keep the power
cord.

We were told that Recycle Ann Arbor now recycles batteries picked up at the
curb.  Would  UPS count?

Probably, as long as they don't mind taking devices *containing*
batteries (instead of just bare batteries.)

The apartment I just moved into has iffy power reliability, so I needed
two more small UPSs, one for the DVR and cable box, and one for a
desktop system.  I didn't need signaling or auto-shutdown, just the
ability to ride through short outages.  I went to RePC and grabbed two
APC Powercells from the "AS-IS" pile.  $3 each.  Testing revealed that
they dropped the load when power was removed, so I went to Vetco and
bought two 12V gel cells for $10 each.  My pair of "new" $13 UPSs work
great.

What size (VA/W)?

These are little ones -- 180W, I think 280 VA.  Or maybe 300 VA.  I've
seen otherwise identical units with identical watt ratings badged both
ways, from APC, so at some point they seem to have changed the power
factor they assume.

I can get bigger ones for the same price but they take a size of battery
that's less readily available to me, and in this case I didn't need the
extra capacity.

Of course, if you can get a *good* APC UPS with only a dead battery, you 
can get the replacement battery from APC (but of course, you would be 
taking a chance that the unit was not OK). I didn't think of trying to 
look for such when my UPS went bad, but a new one still cost less than the 
one I was replacing, and had additional features (like a replaceable 
battery).

The batteries are all standard gel-cell sizes -- you can get them from
APC, Digi-Key, Mouser, Batteries Plus, etc.  It's just that Vetco (a
local electronic surplus place) stocks one size at a particularly good
price, so I tend to seek out the units that take that size.  When I
lived in Ann Arbor I used to buy them from Batteries Plus on Packard,
which stocked a lot of sizes but had somewhat higher prices.

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