Generally, a D battery has a squat and solid barrel-like shape. It is the largest type of cell battery on the market. It has terminals at its opposite ends made of a distinct metal cap. The protruding end is positive, while the other end is the negative cap. A standard D size battery has a diameter of 1.3 inches/33.2 mm and a length of 2.42 inches/61.5 mm. Most D battery types have an average weight of 160g to 180g. Since they are larger than other batteries, they are ideal for applications requiring high power levels over an extended period. Such continuous power consumption could quickly drain the smaller cells. Nonetheless, you need a reliable product to maximize its efficiency. Inferior quality products are worth avoiding because they may leak or develop functional issues after a few days of use.