OK, so admittedly, I know very little about how these things work, so forgive me if this is just impossible. But...have any of you ever wished you had a LIon cell available that was twice the length of an 18500 or 17500? There are so many LED lights that run effectively on 3.7V (just one cell) these days. I've replaced just about all of my 2xRCR123 lights with 1x17650. More run time, and only one cell to deal with makes me happy. But I've got several 2x17500 lights, and it would be great to replace those with a single cell. Anyone else think the same?