[Cerowrt-devel] Low Power UPSes (Was: Re: [Bloat] Dave Täht quoted in the ACLU blog)

Joseph Swick cerowrt at decoy.cotse.net
Sat Jun 28 12:16:30 EDT 2014

On 06/28/2014 12:28 AM, Dave Taht wrote:
> Pretty sure (haven't booted it yet) the parallella (which is smaller
> than a drive),
> can do it in under a 2 watt, and if it doesn't do gigE now, it'll do
> it after I get through
> with it - but it lacks a sata port, and usb is only 2.0, so it might
> not drive gigE
> from a nas perspective. (It kind of bugs me that most of the tiny boards are in
> the altoids form factor, rather than the 2.5 inch drive form factor)
> So I go back to my original point in that, once you have fiber to the business,
> for most purposes in a small business or startup or home - who needs
> to co-lo in a data center?
> You can have a tiny wart on the wall do most of the job. And that's
> today. In another
> year or so we'll be over some more tipping points.
> One thing that does bug me is most UPSes are optimized to deliver a large
> load over a short time, a UPS capable of driving 5 watts for, say, 3 days is
> kind of rare.

I think this is something that's in need of a new approach/disruption.
For low power devices like NUCs and RasPi servers, running them off of a
traditional UPS is hugely waste-full, since you're going from your Line
voltage (120VAC or 240VAC in many places) to 12 or 24VDC (Or 48VDC for a
bigger UPS).  Then when the UPS has to kick in, it converts the battery
voltage back to your line voltage.

A better approach would be to have a UPS that had a good intelligent
charger for your deep-cycle type battery that coming off the battery,
you kept it at the correct DC level for your NUC or Raspi.  Which for
many of these devices is 5 or 12VDC.  So in a sense, it becomes your
low-power device's power suppy, it just happens to have the added
benefit of having a built-in backup battery.

Coming from a Ham Radio perspective, some hams run their base stations
off of deep-cycle marine batteries with some form of charger keeping
them topped off.  This way, the radio operator can operate his or her
station for days just on emergency power.  Since a lot of ham gear is
designed to operate off of 12VDC (with some notable exceptions like your
high-power amplifiers).

It shouldn't be hard to develop a decent grade Low-power UPS for home or
small office use that can run these low power devices for days at a time
with out all the inefficiencies of converting VAC to VDC and back again.
 And there's probably a bunch of Raspi (or similar low-power computer
boards) enthusiasts who already have for their own personal use.

- Joseph Swick

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