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.
Step 2: Plug the Ground pin in with 22-24 gauge solid core wire.
Black wire is recommended to avoid confusion.
The wire will connect the Ground on the Arduino to the Ground on the Lithium Backpack.
Step 3: Plug the +5V pin in with 22-24 gauge solid core wire
Red wire is recommended to avoid confusion.
The wire will connect the +5V pin on the Arduino to the +5V pin on the Lithium Backpack.
Step 4: To power your Arduino flip the switch to the right position
Step 5: The USB port on the Backpack is used to charge the Backpack
The switch should be flipped to the left position (Charg) when charging the battery.
The orange led will be on when the battery is charging.
The Backpack can be charged in 3 different ways.
1.) Through the USB Type B-Mini Female port on the Lithium Backpack when it is attached to a computer.
2.) Through the Arduino when the Backpack is plugged into the Arduino and the Arduino is plugged into a computer.
3.) Through the Arduino when the Backpack is plugged into the Arduino and the Arduino is plugged into a wall power supply.
For more detail: How to Install the Arduino to the Lithium Backpack
French 
English