Date: Thu, 23 Feb 2006 20:15:36 -0500
From: jludwig <wralphie@xxxxxxxxxxx >
Subject: Re: [OT] Cannot save BIOS settings
To: For users of Fedora Core releases <fedora-list@xxxxxxxxxx>
Message-ID: < 200602232015.37404.wralphie@xxxxxxxxxxx>
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On Thursday 23 February 2006 19:17, Tod Merley wrote:
> > Date: Thu, 23 Feb 2006 16:51:28 -0500
> > From: "James He" < icrazy@xxxxxxxxx>
> > Subject: [OT] Cannot save BIOS settings
> > To: fedora-list@xxxxxxxxxx
> > Message-ID:
> > <fd0f51b90602231351h361b635cx4da7fce0941a8534@xxxxxxxxxxxxxx>
> > Content-Type: text/plain; charset=ISO-8859-1
> >
>
> 2. Measuring the actual CMOS battery voltages - with a volt meter out of
> box and with a simulated load if I could figure out with that was (if it
> holds with a 1K resistor my guess is that it is fine). I would also look
> into measuring it as it feeds the CMOS on the MB (very carefully of
> course!!).
>
!
>
> Tod
These batteries deliver micro-amps. Maybe a 100k resistor.
(They usually last 3 to 5 years in service.)
Your point is well taken. I stand well corrected.
The technical specifications of a typical 2016 battery can be found at:
A couple of interesting things here. One is that your 100K resistor will load the poor little critter down to about 2.8 volts at room temperature (see the operating voltage verses load resistance curves) and a second is that typical "skin resistance" I have measured often in the 100K range (it varies from about 2M on very dry tough skin down to a couple of K if people are sweating) and that cheap meters I have seen have "ohms per volt" rateings of as low as 1K. So on the three volt scale the meter would load 3k making the measurement.
Thanks for the help!
Tod
