Casio CZ/ VZ/ FZ - Pro Series

>Sofar it works well, but now I do wonder: would it be wise to install
>a 6 volt 1400 mAh (1400 mAh should be safest) nicd battery, connect
>it to the power supply input so that the battery can charge when the
>psu is plugged in?
>I know it can be don rather easily, but would it work? Would I not
>have to worry about the CZ losing patches for atleast a few years?

You should read up on NiCd charging techniques first.  Not that I'm any kind 
of expert but I think connecting directly to a power supply isn't the best 
approach.