You could put a diode in series with the battery pack to drop the voltage by .7V then have some sort of power monitoring circuit that shorts the diode out when the power drops by .7V.  This may extent useage of the battery pack, depending on what the trade off is for current draw for a power monitoring circuit.

Crazy idea, but may be fun to try

-----Original Message-----
From: Jinx [mailto:joecolquitt@CLEAR.NET.NZ]
Sent: Wednesday, January 29, 2003 3:56 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC]: running on 4 AA batteries?


> OK, so it's not 5.0V, let alone 5.00V, but as long as it's stable
> and inside the PIC's spec for operation, and HI/LO stay completely
> distinct, what's the worry?
>
> Tim Forcer
> University of Southampton, UK

Tim, just a comment. Battery voltages can be a royal PITA. A fully
charged AA pack will have 6.5V (or more), which unfortunately is
the max rating for PICs. As in a reply to the "Linear regulation
question" thread, the series diode will have to pass the current that
the PIC uses, and this is lost power. Although it may be pushing it,
if I had to use a diode it would be a Schottky, just to get below 6.5V.
Not by much admittedly, but the power losses would be less

=======================

BTW, I lived in Gosport for many many years and some of my
best memories are from live bands at Southampton University
and Portsmouth Guidhall

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http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.