Battery pack housing and packaging

A battery pack comprising:

• a first battery disposed in a first housing part and including a first plurality of cells connected in series;
• a second battery disposed in said a second housing part and including a second plurality of cells connected in series;
• wherein said first battery and said second battery are operable in a storage mode and a use mode, said storage mode including isolating said first plurality of cells from said second plurality of cells, said use mode including electrically connecting said first plurality of cells to said second plurality of cells and defining a voltage and a storage capacity for the battery pack;
• and
• a mechanical interface that couples said first housing part directly to said second housing part to form the battery pack;
• wherein at least a portion of said mechanical interface is formed on said first housing part and a remainder of said mechanical interface is formed on said second housing part, and said mechanical interface enables said first housing part to be physically disconnected from said second housing part in said storage mode, and said first housing part and said second housing part to be physically connected in said use mode.