The myth of the memory effect- was: NMIH batteries - was: Re: HP 25 and HP55

Hi Tom ---snip--- ---snip a lot of good stuff--- Thank you for mentioning this. I think, a lot of what people think of as memory is caused by unequal charging of battery stacks. As the cell that has the most charge remaining reaches full charge, the current through this cell reduces. The cell that has been lagging behind, never receives a full change. Flattening the stack lets them all start from a more equal playing field. The problem people miss with flattening is that if a cell is reverse charged, the depolarizers are at the wrong ends of the cells and the gas pressure builds up causing the burst seal to fail. Although, immediately after charging, this cell seems to work fine, within a month or so the cell will fail, simply because it dries out inside :( It may also leak on things. As I stated before, long term storage of NiCads is best done with them fully discharged. This keeps metal fingers from developing that cause the shorted cells that we often see. One can also store them at full charge because this tends to blow out any metal fingers that grow. The problem is that storing mostly discharged cell is the worst since there is both the voltage that causes the metal fingers to grow and not enough capacity to blow them out when they do short. Dwight