.... Pick a voltage that lets you use a more efficient and quieter topology. If maximizing NiMH cycle life is a consideration, there's something to be said for single-cell; it eliminates reverse-charging, the leading cause of cell mortality in multi-cell apps, I suspect. --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .