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From: danny@alice.UUCP ( Kahn @ Bell Communications Research, Murray Hill, NJ)
Newsgroups: net.analog
Subject: Re: Rechargeable Batteries
Message-ID: <3118@alice.UUCP>
Date: Wed, 21-Nov-84 15:43:56 EST
Article-I.D.: alice.3118
Posted: Wed Nov 21 15:43:56 1984
Date-Received: Thu, 22-Nov-84 07:33:23 EST
References: <3292@rabbit.UUCP>
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 20

The articles on rechargeable batteries (ni-cads) have been excessively
negative.  I have used many different brands thru dozens of cycles with
no degradation.  (Of course, there may be some really poor products
on the market that I haven't seen.)

Be sure you are following instructions when recharging.  Overcharging
(excessive time or current) can damage nicads; undercharging will
obviously not give full performance.  Where several cells in series,
recharge when even only one cell discharged, otherwise weakest cells
will be reverse-charged by stronger ones, with possible permanent damage.

As Jan Wolitzky points out, most nicad replacements for ordinary batteries
have same number of CELLS, thus lower open-circuit terminal voltage;
in some applications, typically low-current voltage-sensitive ones,
this can be a problem.   However nicads have very low internal resistance
compared to carbon-zinc or alkaline, so may deliver close to, as much,
or more voltage PER CELL than the other types in high-current applications.
Thus a cell-for-cell replacement by nicads is often appropriate in spite
of the drop from 1.55 to 1.25 open-circuit voltage.