This is one individual littleBits bit: The coin battery is slightly larger than the battery inside your watch! Only with this one, the battery is rechargeable! When you flip the little switch, the red light comes on so you know you have power.  Whenever power is low, plug in a micro usb cable.  The yellow light will come on and the battery will charge. When the green light goes on, then you know it’s ready. What’s littleBits? littleBits is a system of electronic modules that snap together with tiny magnets for prototyping and play.

Check out the detailed electrical diagrams on GitHub.