Re: NTLK Re: Batts in the freezer

From: NewtonOz (newtonoz@ix.netcom.com)
Date: Sun Jul 09 2000 - 19:38:12 CDT


Your eM@il from ratinox@peorth.gweep.net on 7/4/00 8:45 PM said this:

>Well, no, because "memory" is a myth. It doesn't occour except in sintered
>plate nickel-cadmium cells of a type used in early telecommunications
>satellites (Telstar and such), and then only under exacting laboratory
>conditions. Modern cadmium paste cells simply do not suffer from charge
>cycle memory. What is frequently called "memory" is in fact permanent
>physical damage to the cell caused by either overcharging or
>overdischarging. Once such damage occours the cell is ruined; there is no
>way to fix the damage. Freezing it will not help, and could cause more
>damage.
>
>Under normal use, cadmium crystals will form within the paste; this reduces
>maximum charge capacity of the cell. THIS IS NORMAL. It is not memory; it
>is the normal life cycle of a NiCd cell. *OCCASIONAL* deep discharge of
>NiCd cells will break up these crystaline deposits somewhat, restoring some
>of the capacity of the cell. But it is perfectly normal for the maximum
>charge of a NiCd cell to gradually decline over time.
>--

Hmm... recalling from chem classes from long ago...

I seem to remember that the crystalization can be counteracted in NiCads
by using a trickle or quick charge that is over the usual voltage. I
can't remember which. But I do remember that using this method decreases
the battery's life anyway, which means it should only be done for
batteries for which you have no replacement. "S.S. Rat" is right, there
is no such thing as a "memory" effect for modern batteries that are used
normally. This is just a catch phrase that has charmed the masses who
know no better.

The best thing for you to do is have at least three sets of batteries.
One set should be in use, one set should be for standby, and one should
be charging. It doesn't matter whether you use the batteries all the way
or not; charge them when you find it handy. The discharge of a NiCad to
the minimum voltage ONCE EVERY 30 or so times will be sufficient to break
the crystals. Most people will do this unwittingly during the course of
the battery's life anyway.

-Oz
of NewtonOz

With NiCads, and regular NiMH cells, you are going to have full discharge
from 27 to 35 days, depending on the battery age.

-The Folks at NewtonOz Items
newtonoz@ix.netcom.com

(818) 781 1009
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