The life of the Lithium Backpack depends on the battery size and current draw of the Arduino application. For more information go to Liquidware.
The Arduino is an open source hardware input and output circuit and the Lithium Backpack is a Ardino accessory that will power the Arduino when it is away from a computer or a wall power. These products are sold at Liquidware for under $34 each.
Step 1: Plug in the battery connector to the board.
The black wire should face the outside (away from the battery).