Just to bring up a common error when referring to IMR cells, IMR cells are LiMn2O4 cells and are often referred to as "LiMn" (Li=lithium, Mn=manganese), not "LiMN". "LiMN" is usually used when referring to certain Li-Ion cells which contain both manganese (Mn) and nickel (Ni) in the positive electrode, which IMR cells do not.
LiMN, or lithium manganese nickel cells, are closely related to (but not quite the same as) the Redilast and AW 2900mAh cells (which are actually Li-NiCoAl), for example. Most of this general family of cells, which tend to also operate at a higher voltage, also contain cobalt in the positive electrode, which IMR cells do not. This fact is mostly why IMR cells are considered to be a "safer" chemistry.
Not nit picking, but rather trying to help keep things more clear when talking Li-Ion cell chemistries. The most common error I see when describing Li-Ion cells, is when running across someone refering to LiFePO4 cells as "LiPo" cells, when in fact "LiPo" refers to "
Lithium
Polymer" cells which are not the same chemistry as LiFePO4 cells however, they are both lithium ion, or "Li-Ion" cells.
With the newer Li-Ion chemistry cells arriving on the scene, even I get the nomenclature mixed up sometimes. Maybe I just did, but I don't think so.
Dave