Those old NiCad rechargeable batteries
I've "got a ton of them", mostly on on power hand tools. I've moved to NiMh on D cells and smaller.
I have had good life (shelf) on NiCad batteries until I purchased a Ryobi 14.4Volt tool set, including electronic fast charger and two batteries.
The tool is perhaps 1 to 2 years old, has seen occassional use, mostly the hand light being the use, and now both batteries have lost capacity. Yes, I know about the memory effect, perhaps to a fault. I have almost always made sure the battery was really down before recharging. This may be part of the problem. So, I've been recycling the batteries for a few days, letting them run down on "their own", with occassional use of the hand light. Then recharge. They seem to be improving slightly.
Any experience/expertise on this subject? In particular I am of the opinion that Ryobi either got a bad batch of batteries, or there's something wrong with the charger.