D battery Wikipedia
A battery s capacity depends upon its cell chemistry and current draw Duracell brand rates its alkaline D cell performance as approximately 20 000 mAh at 25 mA draw but about 10 000 mAh at 500 mA draw This effect is generally less pronounced in cells with NiMH chemistry and hardly at all with NiCd Many commonly available size D rechargeable cells are actually sub C cells in a D sized holder