Any nicad experts out there? This is an interesting one. (I'm not looking for a "solution", just an explanation, out of curiosity.)
Many years ago I bought the Sony TCD-D3 DAT Walkman, which fits a fat pocket. I made a few live recordings, as it was a lot less bulky than a processor/VCR system.
The other day I pulled it out to confirm it was still working. I'd bought two extra batteries with the unit, and put all three on charge. They all charged up, but the third battery wouldn't power the unit. Its end-of-charge voltage was nearly 7V (though these batteries are nominally 6V), and the other two charged to about 6.4V.
When I put the third battery on charge again, it rose to about 7.5V, even before charge was terminated. I let it sit overnight, and it self-discharged (?) to about 5.5V. (The others //did not// show significant self-discharge.) It still wouldn't power the unit.
"Obviously" this battery pack is defective. I'm just wondering if anyone knows what's going on.
It's no big deal, as I have two good packs (which are 20+ years old!), and the AC adapter. Also, the packs are "external", so I could (if I wanted) saw open the pack and replace the cells. Or simply throw together a homebrew pack to fit the DC jack.
Just askin'.
"We already know the answers -- we just haven't asked the right questions."
-- Edwin Land