From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp73.iad3a.emailsrvr.com (smtp73.iad3a.emailsrvr.com [173.203.187.73]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id EF28421F279 for ; Mon, 30 Jun 2014 05:00:17 -0700 (PDT) Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp18.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id 6286B330075; Mon, 30 Jun 2014 08:00:16 -0400 (EDT) X-Virus-Scanned: OK Received: from app40.wa-webapps.iad3a (relay.iad3a.rsapps.net [172.27.255.110]) by smtp18.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id 1AFE23300CC; Mon, 30 Jun 2014 08:00:16 -0400 (EDT) Received: from reed.com (localhost.localdomain [127.0.0.1]) by app40.wa-webapps.iad3a (Postfix) with ESMTP id E891C302D30; Mon, 30 Jun 2014 08:00:15 -0400 (EDT) Received: by apps.rackspace.com (Authenticated sender: dpreed@reed.com, from: dpreed@reed.com) with HTTP; Mon, 30 Jun 2014 08:00:15 -0400 (EDT) Date: Mon, 30 Jun 2014 08:00:15 -0400 (EDT) From: dpreed@reed.com To: "David Lang" MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_20140630080015000000_17662" Importance: Normal X-Priority: 3 (Normal) X-Type: html In-Reply-To: References: <53A9D92B.7010603@hp.com> <16169.1403645906@sandelman.ca> <8aeaf238-4612-410e-8d07-38159873ea17@reed.com> Message-ID: <1404129615.949824869@apps.rackspace.com> X-Mailer: webmail7.0 Cc: cerowrt-devel@lists.bufferbloat.net, bloat@lists.bufferbloat.net Subject: Re: [Cerowrt-devel] =?utf-8?q?Low_Power_UPSes_=28Was=3A_Re=3A__=5BBlo?= =?utf-8?q?at=5D__Dave_T=C3=A4ht_quoted_in_the_ACLU_blog=29?= X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 30 Jun 2014 12:00:18 -0000 ------=_20140630080015000000_17662 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable =0AGood suggestions. Also, if you have 12V charging the relevant battery, = you can power 5V stuff with a cheap, off-the-shelf UBEC. In a system I bui= lt recently, I powered a Wandboard, an SSD (SSD's typically only use their = 5V supply) and an 8 port GigE desktop switch with one that puts out 5@5V:= =0A =0Ahttp://www.robotmarketplace.com/products/0-DYS30055.html.=0A =0ATher= e are lots of UBEC's out there in the robotics and radio control suppliers.= Motors and batteries like to be higher than 5V, and the electronics and sm= all servos like 5V. You could design your own, but why bother...=0A =0A = =0A =0A=0A=0AOn Sunday, June 29, 2014 11:45pm, "David Lang" = said:=0A=0A=0A=0A> On Sat, 28 Jun 2014, Joseph Swick wrote:=0A> =0A> > On = 06/28/2014 12:28 AM, Dave Taht wrote:=0A> >>=0A> >> One thing that does bug= me is most UPSes are optimized to deliver a=0A> large=0A> >> load over a s= hort time, a UPS capable of driving 5 watts for, say, 3 days=0A> is=0A> >> = kind of rare.=0A> >>=0A> >=0A> > I think this is something that's in need o= f a new approach/disruption.=0A> > For low power devices like NUCs and RasP= i servers, running them off of a=0A> > traditional UPS is hugely waste-full= , since you're going from your Line=0A> > voltage (120VAC or 240VAC in many= places) to 12 or 24VDC (Or 48VDC for a=0A> > bigger UPS). Then when the UP= S has to kick in, it converts the battery=0A> > voltage back to your line v= oltage.=0A> >=0A> > A better approach would be to have a UPS that had a goo= d intelligent=0A> > charger for your deep-cycle type battery that coming of= f the battery,=0A> > you kept it at the correct DC level for your NUC or Ra= spi. Which for=0A> > many of these devices is 5 or 12VDC. So in a sense, it= becomes your=0A> > low-power device's power suppy, it just happens to have= the added=0A> > benefit of having a built-in backup battery.=0A> >=0A> > C= oming from a Ham Radio perspective, some hams run their base stations=0A> >= off of deep-cycle marine batteries with some form of charger keeping=0A> >= them topped off. This way, the radio operator can operate his or her=0A> >= station for days just on emergency power. Since a lot of ham gear is=0A> >= designed to operate off of 12VDC (with some notable exceptions like your= =0A> > high-power amplifiers).=0A> >=0A> > It shouldn't be hard to develop = a decent grade Low-power UPS for home or=0A> > small office use that can ru= n these low power devices for days at a time=0A> > with out all the ineffic= iencies of converting VAC to VDC and back again.=0A> > And there's probably= a bunch of Raspi (or similar low-power computer=0A> > boards) enthusiasts = who already have for their own personal use.=0A> =0A> I think a lot of peop= le are just using li battery packs with USB output to run=0A> their Pi type= computers, with a wall charger into the battery pack.=0A> =0A> it may not = be the best thing for the batteries, but it's off-the-shelf and=0A> cheap.= =0A> =0A> for 12v computers, it's easy to just float a gell-cell on the out= put of a power=0A> supply. If you want to be a purist, have some sort of cu= rrent limiting resister=0A> so that when the battery is extremely low you d= on't overload the power supply,=0A> but in practice, the power supplies are= cheap (getting hold of an old PC power=0A> supply is probably free, and th= ey tend to have a fairly heafty 12v output), and=0A> gell cells are pretty = forgiving of abuse, so you can get away with the=0A> dirt-simple PS -> batt= ery -> device the vast majority of the time.=0A> =0A> It helps that "12v" e= quipment tends to actually be speced to run off of=0A> automotive power, wh= ich is about the ugliest power source you can deal with.=0A> =0A> David Lan= g=0A> _______________________________________________=0A> Cerowrt-devel mai= ling list=0A> Cerowrt-devel@lists.bufferbloat.net=0A> https://lists.bufferb= loat.net/listinfo/cerowrt-devel=0A> ------=_20140630080015000000_17662 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

Good suggestions.  Also, if you have 12V cha= rging the relevant battery, you can power 5V stuff with a cheap, off-t= he-shelf UBEC.  In a system I built recently, I powered a Wandboard, a= n SSD (SSD's typically only use their 5V supply) and an 8 port GigE desktop= switch with one that puts out 5@5V:

=0A

 

=0A

http://www.robotmarketplace.com= /products/0-DYS30055.html.

=0A

 

=0A

There are lots of UBEC's out there in the= robotics and radio control suppliers. Motors and batteries like to be high= er than 5V, and the electronics and small servos like 5V.  You could d= esign your own, but why bother...

=0A

 

=0A

 

=0A

 

=0A=0A



On Sunday, June = 29, 2014 11:45pm, "David Lang" <david@lang.hm> said:

= =0A
=0A

> On Sat, 28 Jun 2014, Joseph Swick wro= te:
>
> > On 06/28/2014 12:28 AM, Dave Taht wrote:
> >>
> >> One thing that does bug me is most UPSes = are optimized to deliver a
> large
> >> load over a s= hort 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 y= ou're going from your Line
> > voltage (120VAC or 240VAC in many= places) to 12 or 24VDC (Or 48VDC for a
> > bigger UPS). Then wh= en the UPS has to kick in, it converts the battery
> > voltage b= ack to your line voltage.
> >
> > A better approach w= ould be to have a UPS that had a good intelligent
> > charger fo= r 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
&= gt; > many of these devices is 5 or 12VDC. So in a sense, it becomes you= r
> > low-power device's power suppy, it just happens to have th= e added
> > benefit of having a built-in backup battery.
&g= t; >
> > Coming from a Ham Radio perspective, some hams run t= heir base stations
> > off of deep-cycle marine batteries with s= ome form of charger keeping
> > them topped off. This way, the r= adio operator can operate his or her
> > station for days just o= n emergency power. Since a lot of ham gear is
> > designed to op= erate off of 12VDC (with some notable exceptions like your
> > h= igh-power amplifiers).
> >
> > It shouldn't be hard t= o develop a decent grade Low-power UPS for home or
> > small off= ice use that can run these low power devices for days at a time
> &= gt; with out all the inefficiencies of converting VAC to VDC and back again= .
> > And there's probably a bunch of Raspi (or similar low-powe= r computer
> > boards) enthusiasts who already have for their ow= n personal use.
>
> I think a lot of people are just using= li battery packs with USB output to run
> their Pi type computers,= with a wall charger into the battery pack.
>
> it may not= be the best thing for the batteries, but it's off-the-shelf and
> = cheap.
>
> for 12v computers, it's easy to just float a ge= ll-cell on the output of a power
> supply. If you want to be a puri= st, have some sort of current limiting resister
> so that when the = battery is extremely low you don't overload the power supply,
> but= in practice, the power supplies are cheap (getting hold of an old PC power=
> supply is probably free, and they tend to have a fairly heafty 1= 2v output), and
> gell cells are pretty forgiving of abuse, so you = can get away with the
> dirt-simple PS -> battery -> device t= he vast majority of the time.
>
> It helps that "12v" equi= pment tends to actually be speced to run off of
> automotive power,= which is about the ugliest power source you can deal with.
>
> David Lang
> _______________________________________________<= br />> Cerowrt-devel mailing list
> Cerowrt-devel@lists.bufferbl= oat.net
> https://lists.bufferbloat.net/listinfo/cerowrt-devel
>

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