Mine came with a mini disc that you put in the computer.... It did contain some kind of instruction, but was difficult to understand. I went by instructions that a previous reviewer had included with his review. Just take a minute to go back through some of the lower starred reviews and you should find it posted somewhere. If I find it, I'll paste it here for you.
The manual indicates that it is a Lithium polymer battery of 220 mAh capacity. It has worked well for me. Charging through a 5 vdc usb port shows a led that changes color once charged. Resolution is rather crude but good enough for my application (vehicle traffic reporting). Brgds. Enrique Laya