Memory effect, also known as battery effect, lazy battery effect or battery memory, is an effect observed in nickel cadmium and nickel–metal hydride rechargeable batteries that causes them to hold less charge. It describes the specific situation in which certain NiCd and NiMH batteries gradually lose their maximum energy capacity if they are repeatedly recharged after being only partially discharged. The battery appears to "remember" the smaller capacity. The source of the effect are changes in the characteristics of the underused active materials of the cell.[citation needed] The term is commonly misapplied to almost any case in which a battery appears to hold less charge than was expected. These cases are more likely due to battery age and use, leading to irreversible changes in the cells due to internal short-circuits, loss of electrolyte, or reversal of cells.