🚀 go-pugleaf

On Sun, 9 Jan 2000 03:36:13 +0800, "Rob" <robstephenson@iname.com>
wrote:

>a minute or so to run yoru battery flat?
>just by having an openconnection?
You need to be careful discharging NiCd's. The phones will shut off
when one of the cells is completely flat. If you go beyond that, you
start reverse charging the  fully discharged cells, and that does
destroys batteries with truly amazing speed.

The memory effect is really a myth. The actually process is well
understood. The problem comes from the intended use in mobile phones.
The rate at which the battery can produce current is related to the
rate at which it run the chemical reaction that produces the
electricity. NiCd's are very attractive because of their ability to
produce high currents even from small batteries (a fully charged AA
sized NiCd can easily put out several amperes. Try that with a dry
cell or an akaline sometime).

NiCd have electrodes that are designed to maximize the surface area,
and believe me, the surface area of an electrode in a high capacity
NiCd is far far higher than the size of the battery would suggest.
Over time the crystaline form of the compounds that store the energy
tend to coalesce, reducing the  surface area where the chemical
reactions take place, and reducing the peak current output. 

So what happens to the battery is the capacity does not change, but
the ability to delivery very high currents for short periods to
operate the transmitter goes away. The memory effect is only seen if
you run the transmit side which demands high current operation. You
will never see it in standby time because for low current operation,
the battery surface area is still adequate. What the full discharge
does is to convert all of the stored energy back to electricity, so
you can reform the storage chemistry, this reforms the  desired small
crystals with large surface area  for maximum peak output, but does
not actually alter the capacity.