Button cells
button cell, watch battery, or coin battery
These are small cell batteries, usually lithium, which are mainly used in small electronic devices such as watches, calculators, car controls, etc. The most common are CR types (C: manganese dioxide-Li. R: round shape). The codes are formed by adding 4 numbers to the letters CR, the first two indicating the diameter of the battery and the next two the thickness (For example CR2032 is a battery with a diameter of 20mm and a thickness of 3.2mm). The most common voltages are 1.5V and 3V
