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From: kaufman@neon.stanford.edu (Marc T. Kaufman)
Newsgroups: comp.dcom.telecom
Subject: Re: Nicad "Memory"
Message-ID: <9931@accuvax.nwu.edu>
Date: 19 Jul 90 16:38:59 GMT
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X-Telecom-Digest: Volume 10, Issue 499, Message 13 of 14


In article <9888@accuvax.nwu.edu> Rob Warnock <rpw3@sgi.com> writes:

>...There is urban legend to
>the effect that you can cure a back-biased NiCd cell by zapping it
>with a very strong (but brief!) forward charging current (as from a
>large capacitor), supposedly to "blow the whiskers", but as I said, I
>consider this in the urban legend category.

Not an urban legend.  *I* have done it several times.  Just use either
the charge from a large capacitor, or (better) a current limited power
supply.  I have a supply I can limit to 3 amps with an 18 volt
maximum.  Attach it to the battery in charging configuration and
slowly turn up the juice.  The current will go up rapidly (into the
shorting whisker) until it fries, then drop back to a more reasonable
value (100 ma or so).  At that point I revert to standard charging
techniques.

I can't tell you about the _ultimate_ service life of a recovered
battery, but it is certainly longer than the remaining life of an
unrecovered cell.


Marc Kaufman (kaufman@Neon.stanford.edu)