The Braille lightweight battery was developed originally for military applications, but was soon adopted by the rally racing crowd. These drycell units have true deepcycle charge capability, meaning that they can be heavily discharged and recharged repeatedly without weakening over time. They weigh 11 pounds and produce 360 cold cranking amps, the same as the stock Cooper S battery. MINI owners have been installing them for the last year or so, but have always had to custom mount them in their car. Now helix has developed a custom Braille battery box specifically designed for the MINI Cooper S. It retails for $49 and is available immediately. Here's a shot of it: