Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: notesfiles - hp 1.2 08/01/83; site hp-pcd.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!ihnp4!pesnta!hplabs!hp-pcd!john From: john@hp-pcd.UUCP (john) Newsgroups: net.micro Subject: Re: Uninterruptible power supplies Message-ID: <6200045@hp-pcd.UUCP> Date: Wed, 13-Mar-85 16:08:00 EST Article-I.D.: hp-pcd.6200045 Posted: Wed Mar 13 16:08:00 1985 Date-Received: Wed, 6-Mar-85 04:36:25 EST References: <362@abnji.UUCP> Organization: Hewlett-Packard - Corvallis, OR Lines: 18 Nf-ID: #R:abnji:-36200:hp-pcd:6200045:000:644 Nf-From: hp-pcd!john Mar 3 13:08:00 1985 <<< < Why not put a diode in series with the batteries? > The problem with this is that it cannot tell whether the power failure was due to an actual failure or simply turning the machine off. In one case you want to supply power and in the other you don't. You need to wire it into the power switch so that it can be disabled and should put in a trickle charger to keep it topped off. Another problem with diodes is their forward voltage drop. If you drop .6 Volts across the diode from a 6 Volt battery then you use 10% of your battery energy in the diode. This means you have to use larger batteries. John Eaton !hplabs!hp-pcd!john