SparkFun PRT-16718

The operating temperature is the range of ambient temperature within which a power supply, or any other electrical equipment, operate in. This ranges from a minimum operating temperature, to a peak or maximum operating temperature, outside which, the power supply may fail.

The most common lithium-ion cell is the 18650 (the numbers define the physical dimensions and shape as follows: 18mm in diameter, 65mm long and the 0 means it has a round cross-section) which is due to its widespread use in laptop battery packs.