D batteries are commonly used in portable music systems, large torches and flashlights, ignition systems for gas heaters, irrigation controllers, and toys. Alkaline batteries have a lifespan of approximately 6 years. The AD battery measures 61 mm long and 34 mm in diameter and weighs 139 grams. They are also available in the rechargeable HR20 model, with the same diameter and thickness; its weight varies depending on the model's capacity. Like all rechargeable batteries, its voltage is 1.2 volts, and its mAh capacity may vary depending on the brand and model.
