Hi Ray.
Read more on the 'myth' (or is it an urban legend?) of NiCad memory on
http://www.a1.nl/phomepag/markerink/battery.htm .
Just a short quote:
> There is something known as the "memory effect", which can
>limit NiCd battery capacity if the battery is _repeatedly_
>discharged to _exactly_ the same partial-discharge level, and
>then fully recharged, many times in a row. Gates[1] states that
>the memory effect is almost never seen in practice, because it
>only occurs if the partial-discharge level is repeated very
>precisely many times in a row.
>
>There _is_ an effect which can mimic the "memory effect", in the
>sense that it makes the battery look as if it is losing capacity.
>This effect, known as "voltage depression", occurs if you
>over-charge a battery. The battery's output voltage drops from
>1.2 to about 1.05 volts partway through the discharge cycle, and
>this may "spoof" a power-monitoring circuit into believing that
>the battery is exhausted.
>
About the use of NiCd's: in particular circumstances, they do a better
job than NiMH's. E.g. when high currents are needed (flashes!), NiMH
doesn't do that well... and of course that self discharge rate, being
up to ten times as high with NiMH's than with NiCd's... Your recharge
discipline needs to be much better with NiMH's, to prevent you from
the unwanted surprise of empty batteries just when you need them!
Frank.
On Thu, 26 Oct 2000 02:18:16 -0700 (PDT), Ray Moth
<ray_moth@xxxxxxxxx> wrote:
>It's not universally known that Ni-Cad batteries develop a 'memory' and
>will not retain a full charge if they are repeatedly 'topped up', that
>is, recharged before they are fully discharged. Ni-MH and lithium ion
>batteries are much better in this regard. The fact that the
>photographic industry still uses NiCads is disgraceful, IMHO. This type
>of battery has long been superseded (yes, that's how you spell it!) in
>the computer industry.
>
>Regards,
>
>=====
>Ray
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