Will
I once worked with an satellite engineer (things that go around the earth, not tv) who swore by reconditioning his nicad batteries by zapping them with a fairly large capacitor. What he would do is ground them for a long period and then charge a fairly large capacitor (I recall about 50-100K microfarad) with a similar voltage as the battery he was trying to condition. He would then discharge the capacitor into the battery causing the structure of the battery to re-align. I have not tried this but I watched him do it, and he swore it made his batteries suffering from hysterisis behave just like new.
I would not try this if you are not technically inclined but it makes some sense that it would work. I guess as the batteries age or go to an absolute zero voltage, the alignment of its structure becomes in disarray causing them to not take or hold a charge.
Bill
www.homeautomationnet.com