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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