UPS that is UN-interrupt-able;!..

One thing that quickly kills lead acid batteries, especially the gel
types, is a poorly controlled, non temperature compensated, float
voltage. Add this to running them at a relatively high rate of discharge
on the few occasions they are used and it will will really show up any
weaknesses. I'd budget for replacing them every year or eighteen months,
then, as has been suggested elsewhere, using them for less critical
applications until they finally fail. The limit would be about a hundred
full charge/ discharge cycles or, as has been said here, three years. In
a car, the battery is normally less than ten percent discharged by a
start, which will give well over a thousand start cycles, as the life is
only limited by other processes with that sort of usage. You can kill a
car battery in a very short time (Weeks, not months) by sitting round
all day using a laptop or other device that will take it below fifty
percent charge on a regular basis, or using your car battery to power
the caravan lights on holiday.

 

Batteries can still be bought for most phones under five years old, of
not older.

I just this week bought a genuine Nokia new battery for a six year old
Nokia 6230 ex-stock from the local fly-by-night phone shop. Just in
time, too, the original was beginning to bulge.....

 

You should be able to find new one on eBay (where I bought a 'new'[1]
phone this week, after all the recent excitement/discussion about phone
shops). Bought it Sunday, arrived Wednesday.

[1] It claims to be in effect an unwanted Xmas present and only used for
two weeks - the vendor left all the data on it and nothing goes back
further than that. Anyway I've flushed it all off now.

 

That's mind-bogglingly modern compared to mine ... yours even has a colour
screen!

However, now that I've bothered to do a search, batteries for my 6250 do
still seem to be available

 

NOTE: The following newsgroups were omitted in my reply:
cam.misc
uk.d-i-y
Neither of these look related to alt.computer.

Many standby or uninterruptible power supplies produce a stepped sine
wave. A stepped sine wave output is satisfactory for the switched power
supplies used for computers. You need true sinusoidal output for
non-switched power supplies to prevent overheating in the step-down
transformer found in non-switched power supplies. To save on cost,
space, and weight, power transformers are usually operated close to
their saturation. The extra dV/dt, or volt-seconds in the square
portion of the stepped sine wave may fully or over saturate the
transformer's core. Only the winding resistance limits the amperage.
With the stepped input, you can get a current spike thorugh the primary
winding and that will heat it up beyond its operating temperature range
with the result the insulation (thin varnish) could melt. Stepped is
okay for computer PSUs but not for other loads.

Besides that stepped output doesn't deliver as much power as a smooth
sine wave, there are also the induced harmonics to consider that can
induce noise in the connected device. As to how inefficient is the use
of the stepped output depends on the size of the steps to determine its
effective RMS value. I haven't owned an oscilloscope for maybe 30 years
to take a look at the typical stepped voltage produced by consumer-grade
standby or uninterruptible power supplies. I've heard (but never
confirmed) that some really cheap UPS units produce square wave output.
I doubt it but others have claimed it. From my readings, they produce
stepped output, so how efficient they are (or how efficiently the output
can be used by connected devices) and much the connected devices get
heated depends on how tiny are they steps (smaller dv/dt is better to
approximate the RMS for a true sine wave) and what devices are connected
as to what type of power supply they use.

Also remember that many "UPS" device are no such thing. Marketers love
to abuse and misuse terminology. Many do not generate the output power.
Many just feed through the line voltage while possibly compensating with
the battery during sags. That is, the "UPS" is actually a standby unit
(SPS) with power conditioning needed to smooth the transfer from line to
battery mode. Often they use this conditioning as an excuse to claim
they also protect against surges. Few UPS'es actually protect against
surges to the devices connected to them and don't have any input surge
protection for the UPS. Real surge protection would add cost to the UPS
(or SPS) and consumers are often guided only by cost.

Most are standby units that flip to full battery power within a few
milliseconds. This is more than long enough to keep the computer
powered up due to the capacitors in the computer's PSU. A UPS (which is
actually a standby unit) that switches in, say, 4ms is more than fast
enough for a computer's switched power supply that has a 100ms lag.
Other devices with lesser regulation may not run without interruption
with these fake UPS units, sometimes called an offline UPS, but is still
just a standby unit. A true UPS generates its own power but that
doesn't equate to true sinusoidal output which usually comes at added
expense due to the use of a hefty isolation transformer (ferroresonant)
or added electronics. The increased cost of a true UPS with its
increased cost, increased power consumption, and increased heat is why
you don't find them in the stores. A true UPS with true sinusoidal
output is even more expensive, and still you may need to employ decent
surge protection before it.

While the OP posted in a newsgroup about computers doesn't mean the
customer isn't plugging in electronics other than a computer. The OP
saying they are working for a "customer" and mentioning wanting a
rack-mounted UPS indicates the customer is a business with a computer
room. Nothing was mentioned about the conditioning of the power fed to
the UPS, what will be the loads (devices) on the UPS, if the source
power minus the power factor for the UPS will provide sufficient
sustained amperage to the devices, and what is the customer's
expectation for behavior from the UPS (how long is the up-time, how long
to recharge, duration of batteries, how to alert on outages or self-test
problems, monitoring software and connection type to host being
protected, etc). Vague scenarios get vague solutions.

 

I've used a variety of UPSes both provessionally and personally over the
years. APC is obviously a major player, and I've used many of their
offerings.

I've come to the conclusion that UPSes are generally less reliable than
the supply they are backing up, and are more or less useless.

You mught get enough run-time for the server to shut down gracefully, if
you are lucky. Otherwise, the UPS may fail when it's required and
dirty-shutdown your kit, or may fail when it's *not* required, and dirty
shutdown your kit.

A pox on them all.

Others will no doubt disagree.

 

You can still get batteries for the wife's Nokia 3210, which is well
over ten years old. It's had one new battery in its life and is
approaching time for another.

 

People still buy mobile phones? What's the point? You can get hand-held
computers scarcely bigger than a mobile phone which do email,
web-browsing, GPS navigation and any number of 'applications' one of
which is to make phone calls, so why would you bother with a dedicated
device for just making calls?

 

My phone fits in the ticket-pocket of my jeans and can be sat on
repeatedly without damaging it, is immune to being scratched and holds
charge for nearly a week.

I neither want, nor need, anything more clever at the moment.

 

Because that's what I want.

 

It's an interesting question. In this case I wanted to buy a gadget that
was mainly a digital camera, but with a phone attached.

Now it's arrived I find it also has GPS and Internet (via 3G or wifi).
So it combines some other gadgets such as you mention. The cost of
running these may be a little high, though (it seems my daily allowance
of data is only 25MB, and I don't seem to be able to plug my 3G dongle
into it).

However, if I want to use a "computer", then nothing less than a "proper
notebook PC" will do, I'm afraid. Even something like an iPad won't "do
email" to the extent that I require. And I quite like looking at web
pages that are bigger than an A4 page, not smaller than a credit card.

And while I can use my laptop to make VoIP calls via my home broadband,
it's not the sort of thing I can shove in my pocket to make "mobile"
calls with.

Anyway, I regard myself as an extremely early adopter, having for
example used mobile data routinely since around 1994 (but only as a
modem attached to a laptop, not using the phone as a display and
computational device as well).

However, I think we need one more generation of screen and battery
technology before I'll be happy to buy a 15" tablet PC/Phone that runs
Windows apps and has enough life to be left on 24x7 in case a call
arrives.

 

Sounds like you are buying cheap and cheerful UPS for £50, when what the
OP wanted was one that retails for more than 10x that amount.

As for reliability of the mains, that depends enormously on where you
live. In an urban area you might get one hiccup a year, often of very
short duration. Go ten miles out into the country and my experience is
significant breaks, several times a year. The difference is whether the
power arrives under ground, or on wires competing with trees, high winds
etc.

 

The general rules I've found which seems to have applied to all the
(non-extended run-time) UPSs I've bought (APC, MGE, No-one el-cheapos)
is that if you run them at half their rated load, then they'll last
for about 15 minutes. Any load above that and it's highly non-linear,
but below that it's fairly predictable.

So that's what I aim for - never run them at more than half the rated
load - and change the batteries every 2 years or so.

Seems to have worked for me - so far!

I've just replaced the cells in 3 small UPSs I have - got them from my
local farm supplies shop - 6 quid cheaper (each) than online for what
I can see is the same make/model...

Gordon

 

Don't you think the fact that iPad/Android tablet devices have rocketed
past almost two decades worth of tablet PCs in less than a year has
pretty conclusively demonstrated that running Windows apps on tablets is
a niche market?

 

That used to be our experience here (University Computing Service), but
our current UPS has been supplying our machine room continuously for
several years now and has carried it through countless minor (and a
couple of major) power cuts.

On the other hand, our UPS is a big and expensive one, and I suspect
that makes a difference.

 

No, it just means that after 18+ years of hype (the Apple Newton dates
to 1993) and 10 years of significant advances in connectivity (the 3G
auction was in 1990) we've finally got to the stage that there's a
significant niche for PDAs with some web applications on them.

But what I need is a proper computer.

I also need a PDA, but currently even the biggest and best tablets still
fall between two stools for me, so a smartphone that's almost now got
the functionality I had in a 1991 HP95, plus a decent camera, saves me
having to carry multiple small items around.

Oddly enough, it was an HP95 that I used at Vodafone's HQ in around 1993
to demonstrate a wireless connection (using one of their phones) to
CompuServe, for genuine mobile email. They'd never seen that before, not
even from their internal boffins. And, of course, being PC compatible,
it wasn't that hard to port a suitable CompuServe compatible client to
facilitate that, but I seem to recall it being a bit tight on RAM!

 

And people wonder why the network operators end up following rather
than leading....

 

Hi Tone,

I've an old APC UPS which powers the server and desktop PC. The
batteries don't last long as you say. It has to be overcharging, but I
can't be bothered to delve into the unit to try and adjust the
charging. I'm told the fire/burglar/water leak alarm industry changes
batteries on a regular basis for this reason (and a regular
maintenance contract income). I suggest every 2years might be
sufficient. Maplin stock a good range of SLA batteries, not sure
about the quality mind you.

Set the replacement date in your diary!

John

 

I did mention that this wasn't a consideration as such, a UPS isn't to
be regarded as a standby power system .. as it happens they only use a
small amount thru it so if it lasts for around half and hour that will
be fine...

 

That does now seem to be the case and in fact they have gone for the
Eaton EX series so job done.

As regarding the ethernet connection totally agree. A Large Mge Ups we
inherited has one of they, and very good and useful it is too..