try zapping you batteries to bring them back to life, here's one of many "how to" sites
http://www.instructables.com/id/Revive-Nicad-Batteries-by-Zapping-with-a-Welder/
It is much safer to store the zapping energy in a large electrolytic
capacitor.
Take a 10,000 to 20,000 microfarad capacitor with a rating of 25
volts or more. Briefly connect the capacitor to a car battery,
observing correct polarity.
Then connect the capacitor to the NiCd cell to be rejuvenated,
again observing polarity (+ to +, - to -). Hold it connected
for a second or so, then disconnect it. Check the DC voltage across
the cell. Repeat a few times if necessary.
When the short is cleared, you will get a substantial
fraction of a volt. Immediately put the cell on a slow charge.
You may get weeks, months or years of extra life. It is
important to inspect each cell in a pack, and to apply this
procedure only to those cells that exhibit a short (nearly zero
voltage).