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From: optilink!elliott@uunet.uu.net (Paul Elliott x225)
Newsgroups: comp.dcom.telecom
Subject: Re: Nicad "Memory"
Message-ID: <9976@accuvax.nwu.edu>
Date: 20 Jul 90 18:03:42 GMT
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X-Telecom-Digest: Volume 10, Issue 502, Message 12 of 15


In article <9888@accuvax.nwu.edu>, rpw3%rigden.wpd@sgi.com (Rob
Warnock) writes:
 
> In article <9807@accuvax.nwu.edu> forrette@sim.berkeley.edu (Steve
> Forrette) writes:
 
> | Can someone recap the discussion of "memory" in nicad batteries?  I'm
> | having a problem with my HT5300 AT&T cordless phone.  I had it
> | [description of battery problem]

> [reverse-charging, etc] 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.

This isn't really a legend; it does work.  Unfortunately, It doesn't
work often or well.  You will occasionally get lucky, but my
experience has been that the restored cell is not reliable, and will
likely have excessive leakage (self-discharge), and will probably
short out again.  If you want a battery you can depend on, just
replace it.

> | It's been charging for over two days, and
> | reads only 2.65 volts.  The battery is rated at 3.6V, 720mAh.  When I

Definitely a shorted cell.  NiCd cells charge up to about 1.3 to 1.45V
when they are charging and fully charged (in the "overcharge" state),
so the voltage you are measuring corresponds to two fully-charged
cells and one shorted cell.


      Paul M. Elliott      Optilink Corporation     (707) 795-9444
               {uunet, pyramid, tekbspa}!optilink!elliott