At 03:39 PM 11/10/03 -0500, you wrote: It depends on what kind of batteries you're talking about. On carbon-zinc and alkaline batteries it's caused by the electrolyte eating through the metal shell. In NiCads it can be caused by the growth of crystals of the metal electrodes. They can pierce the seals. Also NiCads have a pressure relief value that can fail and allow the electrolyte to leak out. Also the electrodes frequently short and cause excessive heat to be gernerated and that causes pressure in the cell, Then the pressure relief value vents, as it's designed to do, and allows pressure and electrolyte to leak out. That's why I don't try to "zap" shorted NiCads. You can usually burn the shorts out of them and get some more life out of them but they will almost certainly leak and I consider the equipment that they're in more important than the costs of replacement battery cells. Joe I am worried