Hi, this is a good solution as a temporary battery that isn't conected to a charging system, as Steven has.
NiCad's go into something called "Thermal Runaway" if you keep charging them and they get hot. I saw this a few years ago when I did solar cars.
There's almost nothing you can do when the reaction gets out of hand.
Brenton - AKA "the fun police"...
'51,'56 Squares, '48 VH, '27 Model C, R67/2, Mk IV Le Mans, '06 Super Duke and Ariel projects.