On 16-Nov-05 Tim Green wrote:
On 11/16/05, Ted Harding Ted.Harding@nessie.mcc.ac.uk wrote:
Can anyone recommend a good place to look for a UPS within reasonable reach of Ely?
So I'm looking for 600+ watts, at least 3 battery-protected 220C power outlets.
One good thing about the Belkin was that its controlling software came also in a Linux version, allowing clean shutdown of connected machines.
I've had a look in PC World in Cambridge, and their current stock of stuff is not up to what I'm after, though maybe I could go for a lower-rated UPS per machine. Not keen on proliferations, though!
Since you made it as far as PC World, how about an APC unit, possibly from WOC? All the Linux support you need is already in most distributions (certainly no trouble with Debian Sarge and USB :-)
APC batteries look easy to replace, but I couldn't comment on their availability.
I've had a look at WOC's wevsite (I assume you mean World of Computers om Milton Road). It does look as though they might have something available in the right range.
Interesting subsequent discussion ...
One question: When I look through especially APC stuff on the Web, I note that they give different numbers for VA and for Watts, e.g.
APC Smart-UPS SC, 620VA/390W, Input 230V/Output 230V, Interface Port DB-9 RS-232
I've always been under the impression (ever since I learned electricity when I was little) that Watts = Volts*Amps, so VA should equal Watts, No? Or have I been living a lie? Or does VA mean something different in this context?
Another question: One thing I could try is simply taking the dying battery out of the Belkin unit, and jump-leading a car battery to the internal battery cables, at any rate as a stop-gap until I can get something else sorted out.
However, as people have been discussing, there's an issue about the power demand when it goes into battery mode. I got the Belkin at 625VA (?Watts) to be on the safe side, but I reckon it would need to stand 400, since I have 2 machines on it along with a few sundries (modem, TFT monitor, cordles phone, and the like).
So, I wonder what a normal car battery (of which I have one spare) can support as peak current?
Since the spec of the Belkin battery is 12V (but no info about current rating) the voltage would be OK.
I also have a small motorcycle battery (12V) which I bought so that I could run a laptop which has a totally shot battery (this machine runs happily on 12V) when not near mains, and the battery keep the laptop going for about 5 hours; but I'd be doubtful about drawing even 240W (20A) from that battery.
But I just don't know what these sorts of basic lead/acid battery can stand. Any knowledgeable folk out there?
I'm not into using the UPS for long-term backup. The real need is
a) To kick in and stabilise the output voltage when the mains voltage droops (fairly frequent)
b) To supply power during brief outages (a few seconds, and pretty frequent, often accompanied by spikes)
c) To supply power for at least 5 minutes when the mains goes down altogether, allowing the machines time to shutdown cleanly under cntrol from the UPS (happens often enough not to be ignorable -- e.g. trees on the O/H cables in storms, farmer ploughs up the U/G cable, "snow on the line", all of which have happened).
So maybe the vehicle battery solution might be OK. Or not?
Thanks, Ted.
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