Q. What is the size of the pencil battery?

The length of an AA cell is between 49.2 and 50.5 millimetres (1.94 and 1.99 inches) which includes the button terminal; its diameter is between 13.5 and 14.5 millimetres (0.53 and 0.57 inches). The flat negative terminal should have a minimum diameter of 7 millimetres and the positive terminal button should be at least 1 millimetre high and no more than 5.5 millimetres in diameter at most.