Article: 10220 of comp.sys.laptops
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From: edler@jan.ultra.nyu.edu (Jan Edler)
Newsgroups: comp.sys.laptops
Subject: Re: Getting rid of Nicad memory effect
Date: 19 Apr 1993 17:57:14 GMT
Organization: New York University, Ultracomputer project
Lines: 27
Message-ID: <1qup5q$scs@calvin.NYU.EDU>
References: <735092474snx@tixel.mv.com>
NNTP-Posting-Host: jan.ultra.nyu.edu

In article <735092474snx@tixel.mv.com> jarnold@tixel.mv.com writes:
>I had posted a note a few weeks ago about how to "fully discharge" a
>nicad battery pack (that powers my notebook pc) that has apparently
>developed the dreaded nicad memory effect.  Brand new, I used to be
>able to get 3+ hours of heads-down work out of a charge, but now
>(same apps, same work habits) I'm lucky to get as much as *one* hour.

I have been using a resistor to regularly discharge my T1000SE battery
for several years.  This is a 7.2V pack.  I use a 10 Ohm power resistor
from Radio Shack.  I remove the battery, place it upside down, place
the resistor on the battery contacts (I've bent the resistor's leads to
make this convenient), and put a little weight on it to make a good
connection.  I normally connect a voltmeter to it, and wait about 10 or
12 minutes for the voltage to drop below 6V.  I keep the voltmeter on
my desk, so this is convenient, but otherwise I just time it for about
10 minutes.  I use a kitchen timer to remind me when to check the
battery.  I go through this procedure almost every time the machine
shuts off, before recharging (i.e., about daily).  This arrangement
seems to work well.

When I started doing this, a few years ago, I drained the battery all
the way (until the resistor was cold).  I never had any trouble, but
various people were making arguments that this could damage the cells,
so now I stop somewhere below 6V.  So far so good.

Jan Edler
edler@nyu.edu