[MetalMan]

A123 cells aren't typic "Li-Ion" cells. Older Li-Ion were 3.6v nominal and 4.1v fully charged, newer ones are 3.7v nominal and 4.2v fully charged. A previous battery chemistry known as LiFePO4 (Lithium Iron Phosphate) had a nominal voltage of 3.2v and a fully charged voltage of 3.65v (but could safely take 4.2v), and was as stable as the A123 cells, and were also in a metal can. I've seen some (on another forum) label the A123 cells as LiFePO4. But anyways, A123s should be kept from charging above 3.60v if possible, although they aren't dangerous if charged to 4.2v.