[Tristan Lall]

Lithium-ion batteries, while nice and light, tend to quietly commit suicide after a few years of existance. Note existance, instead of use. Even in storage, they deteriorate. Unless some new formulation has been employed here, it is quite possible that the battery will be useless within two to five years, depending on various conditions (type of discharge, storage temperature, etc.).

It's the same problem seen with laptops and some cellular phones. The battery starts losing capacity, and eventually won't accept a charge.