A NiCad battery (also written NiCd) is a rechargeable battery made with two metals, nickel and cadmium. For years they were common in cordless phones, power tools, cameras and other small electronics, because you could charge them again and again. Though actually, they have a well-known quirk called memory effect: if you always top them up before they are empty, they can start to hold less power. Cadmium is poisonous, so these batteries should not go in ordinary household rubbish, and many places have stopped putting them in everyday gadgets. Newer packs are often NiMH or lithium-ion. People still say NiCad for the old type, and repair shops still meet them in older machines.