From owner-freebsd-questions@FreeBSD.ORG Sat Nov 29 04:12:18 2014 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id A62AFBCD for ; Sat, 29 Nov 2014 04:12:18 +0000 (UTC) Received: from alogt.com (alogt.com [69.36.191.58]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 7AD3CF71 for ; Sat, 29 Nov 2014 04:12:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=alogt.com; s=default; h=Content-Transfer-Encoding:Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Subject:Cc:To:From:Date; bh=VoUf7oZMUaPFoFwDyOyXlApEdJKtTNmdaxBYLwlPxEU=; b=tKjRfrm0Nuj+xprBafiB/lyLuW7z2gZXFEi3Pfc1fWItk96HNxMkOPZge5C4a1QykM2bvPkjjtx4B73aM0HVniVbkfp1gNk/DJNjcW5Y6AhdmtBo2zym8dD2j1zHB7MhZaUQDSwaXh9c6eGkx6BnNFHARkMSEVHL/dnJzI39sbk=; Received: from [114.121.160.118] (port=27745 helo=X220.alogt.com) by sl-508-2.slc.westdc.net with esmtpa (Exim 4.84) (envelope-from ) id 1XuZOJ-003MhH-P6; Fri, 28 Nov 2014 21:12:16 -0700 Date: Sat, 29 Nov 2014 12:12:11 +0800 From: Erich Dollansky To: Jon Radel Subject: Re: OT: UPS for FreeBSD Message-ID: <20141129121211.014cb856@X220.alogt.com> In-Reply-To: <547937AB.1030706@radel.com> References: <54777AB1.9010800@bluerosetech.com> <54779629.302@bluerosetech.com> <5478BD4F.7020306@yahoo.com> <5478BEE6.30308@bluerosetech.com> <5478CC08.9090307@yahoo.com> <20141128204722.561f948e@archlinux> <5478F16A.80605@yahoo.com> <54791d3a.w/pI0kak03d+3nKC%perryh@pluto.rain.com> <547937AB.1030706@radel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - sl-508-2.slc.westdc.net X-AntiAbuse: Original Domain - freebsd.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - alogt.com X-Get-Message-Sender-Via: sl-508-2.slc.westdc.net: authenticated_id: erichsfreebsdlist@alogt.com X-Source: X-Source-Args: X-Source-Dir: Cc: Michael Sierchio , FreeBSD Questions X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 29 Nov 2014 04:12:18 -0000 Hi, On Fri, 28 Nov 2014 22:04:11 -0500 Jon Radel wrote: > On 11/28/14, 8:26 PM, Michael Sierchio wrote: > > I've always found it amazingly absurd that you use a UPS (a bank of > > batteries charged by AC->DC conversion), invert it back to AC, > > which gets converted to DC for the motherboard and peripherals. > > > > But that's just me, probably. > > Hardly. See > http://hightech.lbl.gov/dc-powering/ > https://gigaom.com/2012/01/13/the-next-big-thing-for-data-centers-dc-power/ > etc. It's not storming the world, but some are doing it. > it is just a hype with two exceptions. Real high voltage transmission lines using DC make sense. Having a DC grid locally could also make sense especially when solar power comes into the game. As all voltage conversations take place via AC, plain DC networks do not and will only very rarely exist. Even solar powered grids need AC for regulating the grid voltage. Erich