<div class="gmail_quote">2011/3/9 Daniel Axtens <span dir="ltr"><<a href="mailto:danielax@gmail.com" target="_blank">danielax@gmail.com</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>> For the UPS' sake, running only for 90 seconds doesn't take the battery<br>
> anywhere near to the UPS' "discharged battery" threshold which, for these<br>
> small SLA batteries, kills them without too many cycles to flat. I suspect the<br>
> UPS manufactures underrate the battery and are relying on the idea that most<br>
> power losses are short.<br>
<br>
</div>This is one of the best thought-out responses I've received to anything this year. Thanks Harry.<br>
<br>
I've also been told on IRC that we do have machines dying due to power issues, and that, to [BOB] at least, not having to rebuild his screen session is worth $1000.<br></blockquote></div><div><br></div><div>What are you guys trying to achieve? �Power conditioning, 2 min uptime, 30 min uptime, or longer?</div>
<div><br></div><div>A well-maintained UPS can be expensive to run. �The equation is something like: purchase cost + electrical install + 2-yearly battery replace/dispose + service costs.</div>
<div><br></div><div>OK, so you can skimp on the last two, but - and I'm hazy on this - dying lead acid batteries will just suck charge continually while not actually charging. �But if it is a (more expensive) double conversion UPS (AC-DC-AC), it will make a nice, but warm, power conditioner.</div>
<div><br></div><div>I'd get a quote for the extra circuit, because it may not be trivial if they don't have capacity upstream.</div><div><br></div><div>My experience with UPSs is that sometimes it is better to have multiple small ones than one big one. �They are more disposable, and operating on common 10A circuits makes the electrics much cheaper (you can also get yourself into trouble with overloading easier, I guess). �Liebert is a good brand but even their service guys warned me that like everyone, they make crappy consumer models too. �One thing I would stay away from are modular UPSs. �APC and Liebert make them where you can hotswap PSUs in and out - the general wisdom is that the hardwired ones are more reliable (hotswap batteries are fine).</div>
<div><br></div><div>I just specced and installed them for a while, hopefully this post will attract comments from others more clued into electricals :)</div><div><br></div><div>,dunc</div>