I connected a AA cell to a “Pigeons Nest” flasher more than a year ago, and used it as a trip hazard marker when it’s dark. The cell was a Kirkland brand from Costco. This had been running up until the end of August, even though I had noticed some ‘hair’ building up on one end from the juice leaking out. The flasher stopped sometime in the first few days of September.
The cell may have been a used cell, I don’t remember. It served its purpose and lasted much more than a year. But the leakage that preceded its death leads me to the hypothesis that many if not most fully depleted cells from Joule Thiefs and other circuits meet their end by leaking and drying up inside.
Most name brand cells say they are guaranteed not to leak. I have carbon-zinc cells from the late 1980s that still have much of their charge left and have not yet leaked. That leads me to another hypothesis that the cells made today are lower in quality than the cells made a quarter century or more ago. Battery technology is not new; it has been around for more than a hundred years. I have old books that describe the way batteries were made back then. A common way to seal the cases was to pour a plug of hot bituminous tar into the case. This was fairly thick and did a very good job of keeping the juice in. Today’s technology is a thin sheet steel case with some plastic seal where the case meets the end contacts. I don’t think this is as good as tar for sealing. Some battery companies still offer guarantees but with restrictions, since some battery powered equipment can be very expensive. Most consumers don’t return the damaged flashlight because the shipping might cost more than the flashlight.
