Does anybody use a UPS?

[ameerat42]

UPDATE!!

Got a new battery - OK, paid $55 for a slightly more powerful one - and the machine now works AGAIN.

Ta for all your replies.
Am().

[Mary Anne]

Curious as to why you needed a more powerful battery.

[ameerat42]

I didn't need it as such, M A, but it gives a slightly longer shutdown time in case of power failure.
(Or it was a sales pitch. Bubble is, in the US they cost as low as $17, while here they start at about $30.)
That was the price at this place, Battery World.

He let me try it first, and it was brand new.

Am.

[Mary Anne]

Thanks for that Am, thats good to know.

[farmmax]

It is good you can go and try it. Makes it a good option. I just have to take pot luck. The batteries I use are $22 delivered each, via Ebay.

[ameerat42]

...The batteries I use are $22 delivered each, via Ebay...

[Mary Anne]

It is good you can go and try it. Makes it a good option. I just have to take pot luck. The batteries I use are $22 delivered each, via Ebay.

Where is the link ?

[Warb]

My first post and it's resurrecting a 2 month old thread!

There are many brands of UPS, some better than others, but they fall in to 2 basic types. An offline UPS feeds mains power straight to the load (computer), and when that mains power varies beyond a set value for voltage or frequency the UPS switches to powering the load from the battery. An online UPS, on the other hand, always runs the load from the battery so there is no switching delay and far less risk of a mains fluctuation reaching the load. Both will, to some extent, protect from high/low voltages, spikes and frequency disturbances as well as total mains failures. The online UPS will do so more thoroughly, but at a far higher price! Historically a "faster" computer, or one with a higher power consumption, would be more prone to upset caused by the offline UPS's switching time, but computer power supplies have got better and are more capable of "smoothing out" minor disturbances so the difference is somewhat less noticeable.

Any consumer grade UPS is almost certainly an offline design. How well it will deal with a varying mains supply therefore comes down to its basic quality, which often (though perhaps less so than in the past) relates to price.

UPS batteries rarely last more than 2 or 3 years, but there is nothing special about them - any battery of the correct voltage will work, though it might not fit in the box! Batteries not designed for "float" usage (where the battery sits at basically full charge all the time) very occasionally have problems, and batteries that are not designed for "deep cycle" use (car batteries, for example, are not designed to be depleted to less than about 80% full) will not last long if the UPS has to run the load too many times. However most UPS's rarely actually power the load from the battery for long enough to deplete it much.

A UPS can therefore be of great value. However there are downsides! A UPS is not 100% efficient, so it adds to your electricity bill - a modern "green" UPS might be 95% efficient when matched to a load, but older or cheaper models, especially when lightly or heavily loaded, can be far worse. 80% efficiency means for every kwh the computer uses you actually buy closer to 1.3kwh. Also a UPS adds another point of failure to your system. With a new, quality UPS the protection gained outweighs the chance of failure. But with each passing year the UPS becomes more prone to failure, and at around the 5 year mark the chance of UPS failure statistically overtakes the benefits.

A good UPS is worthwhile, especially if you have a poor mains supply.

1/ Pick one that has sufficient power output (VA) to drive your critical loads (computer, monitor, external disks) but do not attach printers etc. (never laser printers, they can cause damage to the UPS). The idea of a UPS is to give you time to carry out a controlled shutdown of your system, not to keep working when the power's out!

2/ Preferably get one that will communicate with your computer and trigger an automatic shutdown, so it "works" even when you're not there. It seems pointless to have a UPS that just dumps the load when it runs out of batteries!

3/ Bigger batteries will support the load for longer, a bigger VA rating will drive a bigger load. Increasing either will increase the cost, but the VA MUST be enough to power the load, whilst battery only needs enough capacity for you to hit save + shutdown.

4/ As always, these devices generate heat. Don't lock them in an unventilated cupboard, or cover them up.

5/ Buy the best you can afford, test it regularly (at the very least: with only your monitor switched on, turn the mains off and check the UPS keeps the monitor going!) and replace the batteries if it fails either it's self tests or your manual test.

6/ Consider whether the extra point of failure of an old or "questionable" UPS is worth the risk!

7/ When the power fails and you're running on batteries, just shut down your computer and go for a walk. Don't try to keep working, you risk the machine crashing when the batteries run out. I have seen many UPS's that have a grossly exaggerated idea of how long they can keep going, and watched them crash (and seen the horror on the users face) whilst showing they still had 15 minutes run time.

8/ To continue from 7/ above, when setting auto shutdowns for a UPS that communicates with the computer, be conservative. The UPS might "think" it can power the load for 20minutes, but that doesn't allow for the unexpected. The battery may not be as good as the UPS expects, or the load may be higher because the computer is working hard. Is it worth trying to gain a couple of minutes at the risk of corrupting your operating system?


My photography skills are basic at best, but I spent many years as a consultant in the IT industry. I hope this helps somebody.

[I @ M]

My first post and it's resurrecting a 2 month old thread!

Definitely not unwelcome to add some valuable points to an older but still relevant thread.

[ameerat42]

Thanks Warb. You covered a few points I did not know.
I certainly do use it conservatively - though not automatically - as I shut down completely (and all power off) if I'm going to be absent for half an hour or more,
and when the power has gone off - twice from memory - I have shut down straight away.
Am.

[Mary Anne]

Yes all good to know and Thanks for that.