John Smith wrote:

Mike,

Draining a nicad battery will not destroy it. In fact, nicads
have a memory effect, through which the battery thinks it is
discharged, when it isn't. The best way to deal with that
situation is to completely discharge the battery once in a while.

Nickel metal hydride batteries, on the other hand, do not have a
memory and can be recharged after only a partial discharge.

The "memory effect" mentioned by many "experts" occurred exactly ONCE
in a satellite system battery that had precisely controlled discharge
and charge cycles. A simple overcharge or slightly deeper discharge
removed any possibility of the "memory effect" The chemistry and
construction of the cells were changed for consumer usage - memory
effect is, for all practical purposes, close to impossible in these
cells.

The effect of reduced NiCad capacity observed in the outside world is
strictly speaking "capacity depression" and is absolutely nothing to
do with partial discharge and topping up over multiple cycles.
Overcharge the battery by a few % and it no longer occurs.


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