"William Sommer****** "

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.


** You are describing the standard "old age" failure mode of most NiCds.

1. The internal resistance of some or all the cells in a pack rises - often
dramatically.

2. The energy capacity drops by a large factor.

3. The pack will not hold charge due to internal leakage.

4. The terminal voltage is depressed, from 1.25V to about 1.2V per cell.

A single overheating event can result in the same outcome - whether by
overcharging or otherwise.

Reason ?

NiCd cells have a small amount of water in them - lose that and the cell is
stuffed.



.... Phil