Well, This Worked. . .So Far

[db5]

The gist of this video is that you can revive dead NiCad batteries by plugging and unplugging the charger over and over until it starts charging https://www.youtube.com/watch?v=A5k0ljHLF58

I didn’t have a dead battery so went to HD where they have a box in front to recycle batteries. They said I could take whatever I wanted so I found a DeWalt 18V XRP pack that fits my charger and plugged it in. The light showed it was charging; I checked in an hour, the light showed it was charged but it was dead. So I recycled the power strip it was plugged into several times and checked in about an hour and it showed it was charged. I used it on a small project and it seems to work fine. I’ll let it sit for a couple of weeks and see if it retains the charge. I’ll let you know.

Either way, dead or alive, I have a battery pack I can now use to rebuild my own.

https://www.youtube.com/watch?v=PtOS5evrqrQ

[garys]

I've seen similar things with the nicads on laptop batteries. They can reach a point where they refuse to charge any more but are still low. I find that when they do that, remove the charger for enough time so the laptop starts to drain the battery down some and then try the charger again. Sometimes that bit of up and down cycling gets them to the point where they take most of a full charge again.
I suspect that it still means that the battery is near end of life.