From owner-freebsd-questions@FreeBSD.ORG Wed Oct 16 21:12:32 2013 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id AEA8BA62 for ; Wed, 16 Oct 2013 21:12:32 +0000 (UTC) (envelope-from frank2@fjl.co.uk) Received: from bs1.fjl.org.uk (bs1.fjl.org.uk [84.45.41.196]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 122A72B3E for ; Wed, 16 Oct 2013 21:12:31 +0000 (UTC) Received: from [192.168.1.35] (host86-163-34-162.range86-163.btcentralplus.com [86.163.34.162]) (authenticated bits=0) by bs1.fjl.org.uk (8.14.4/8.14.4) with ESMTP id r9GLCNUv081173 (version=TLSv1/SSLv3 cipher=DHE-DSS-CAMELLIA256-SHA bits=256 verify=NO) for ; Wed, 16 Oct 2013 22:12:24 +0100 (BST) (envelope-from frank2@fjl.co.uk) Message-ID: <525F0138.1020304@fjl.co.uk> Date: Wed, 16 Oct 2013 22:12:24 +0100 From: Frank Leonhardt User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: freebsd-questions@freebsd.org Subject: Re: UPS buying suggestion References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.14 X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Oct 2013 21:12:32 -0000 On 16/10/2013 03:43, yudi v wrote: >> These are very expensive UPS systems when new, but can sometimes be found >> at school and local government auctions for about 3% of retail price. The >> batteries are always bad, but not difficult to replace. Well, the rackmount >> ones are stuck in with double-sided tape, and take some convincing. These >> are standard sealed lead-acid batteries, used for building emergency >> lights, alarm systems, and well, computer UPSes. >> >> Sounds wise but unfortunately I cannot find any used ones. > > >> The Back-UPS units are better than nothing, but avoid the fat power strip >> style. >> > why would you say avoid the fat power strip ones, they are the low end ones > but they have the standard plugs unlike the more expensive ones. > I really don't want to spend more than $200 ore even less if possible. My > server only cost me $500. > > As I have mentioned previously someone wants to sell an unwanted APC > Smart-UPS SC 420VA > 230V, > they got with their new PC for half price, I am thinking of going for it. > At the risk of going off-topic: as Warren has pointed out, not all UPS units are the same. In fact, many units calling themselves a UPS are actually backup power supplies, which switch over to battery if the mains fails. Common usage definitions vary, but to my mind, in USP the output should be supplied by the battery all the time, while the mains constantly recharges, so there is no switch-over whatsoever. The quality of the mains voltage they produce also varies - it might be a pure sine wave (as if the mains always was!), or it might be something else. If it's going through a switched-mode power supply afterwards I don't see this as a big issue - the only thing I'm worried about is whether it keeps the computer (HP Microserver - back on topic briefly) running when Gonzo does something to the mains. Audio amplifiers and radio equipment might be another matter, but the switcher found in practically every computer does such unspeakable things to the input mains anyway I can't get to excited about how close to a sine wave the output actually is. Regards, Frank.