[AusNOG] Who makes good UPS gear besides APC?

[Ross Wheeler]

> Is anyone considering fuel cells a suitable replacement for UPS?

12 years ago, viable fuel cell tech for ~1000-5000 watts was 2-3 years 
away. Now it seems even further away than it was then, and even more 
costly. Most of the cells I've seen are wanting "6 nines" fuel purity and 
that's expensive.


> On the same point regarding alternative power sources; considering DC power
> is more efficient (i.e. no loss wasted on conversion), why aren't more
> people going down the route of DC powered servers and storage ?

Superficially, DC seems simpler, more efficient and more straightforward, 
but batteries are funky things. There are a plethora of considerations - 
most of them bad - for datacentre type use. Size, space and weight - when 
you're paying for space, battery efficiency when you're paying for power, 
additional heat, larger cable sizes, more difficult to work on and with, 
more expensive switchgear, less common equipment to use it.

Batteries don't hold a nice, neat, clean x.x volts so still need power 
"supplies", their charging and floating requirements are demanding, they 
have limited cycle life and require periodic replacement, additional 
maintenance, and lets not even get started on the problems of emissions 
from cells (unless fully sealed). Sealed cells are even more finniky with 
their voltages, temperatures etc.

There's hazardous materials considerations, there's also the consideration 
of power remaining on in a rack during say, a fire...



> A couple of rectifiers and some deep cycle batteries would be overkill 
> for most small requirements.

My own office has a a primary bank of Lithium FerroPhosphate cells, and a 
backup bank of AGM lead-acid cells (48 x 2V/500AH). I'll be phasing out 
all the AGMs and replacing with LFP. Nothing of any consequence is running 
off the (nominal) 48V DC because it's simply not suitable nor practical.
Everything runs from 240VAC, even if 99% of things convert it back to low 
voltage DC internally (or through power bricks).

Redundant 240VAC supplies are (IMO) a better solution than running 
everything off batteries.

(Might be different for a few hundred watts of load maximum)

R.