AVR-Chat

>
>One of the problems with maintaining rechargeables is the "memory"
>effect that's certainly evident in NiCd.

Memory, refers specifically to the voltage droop that happens near a point 
of previously repeated discharge.
Long term overcharge causes charge depression in NIMH, but I don't know if 
that happens in Nicad.

>If one isn't stuck for space and weight isn't a problem, then it may
>be appropriate to run two battery packs in tandem; one which is the
>backup supply and the other being cycled so as to avoid the memory
>effect.

Simply sitting on charge will not induce memory in either chemistry.  It 
will induce charge depression in NIMH cells.
Cycling to a specific voltage point, is how I have induced memory previously.
I am going to try this again, discharging to a specific energy point ( say 
to 10,000J discharged perhaps) but that won't be soon.
I'm not at home.


>Full redundancy requires 3 battery packs as the power supply
>requirements to charge a NiCd to make it forgetful is quite high.

???  I haven't tested Nicad yet, but NIMH forgets the memory effect in one 
normal discharge.

>There'd be "backup", "source" and "cycle" packs.
>The source battery pack is used for the initial current supply while
>the voltage of the cycle pack being charged is low. The boost
>current from the source battery depletes a large part of it's charge
>so a backup pack is required for "fail-safe".

And now you have all this extra complexity to fail. :-P