Path: utzoo!utgpu!jarvis.csri.toronto.edu!neat.cs.toronto.edu!ephemeral.ai.toronto.edu!bradb
Newsgroups: comp.sys.handhelds
From: bradb@cs.toronto.edu (Brad Brown)
Subject: Re: Want HP-28S fuel gauge, program name query
Message-ID: <89Dec29.115728est.2641@neat.cs.toronto.edu>
Organization: Department of Computer Science, University of Toronto
References: <4374@rtech.rtech.com>
Date: 29 Dec 89 16:58:16 GMT
Lines: 23

glenk@llama.rtech.UUCP (Glen Kilpatrick) writes:


>*  What about a "fuel gauge" for the 28?  I'd like a function that
>would return a real number between 0 & 1 indicating battery voltage,
>where 1 = new batteries, & 0 means the low-battery indicator was
>just triggered.  If it could report hours of continuous computation
>left, it would be a googol times GREATER (but that's too much to
>hope for!)!

This would be really hard to do.  Alkaline batteries tend to have 
fairly constant output for most of their life then they drop off
quickly.  This is similar to what happens with NiCad batteries,
except NiCads drop off much more rapidly...

Consiquently, it would be hard to accurately measure remaining
charge from battery voltage.  On IBM-PC compatable laptop computers
you can get a utility that loads as a background program and monitors
system use to keep track of battery drain.  That approach doesn't 
seem practical for the HP-28 :-)

					(-:  Brad Brown  :-)
					bradb@ai.utoronto.ca