self-discharge

Self-discharge is a phenomenon in batteries. Self-discharge decreases the shelf life of batteries and causes them to have less than a full charge when actually put to use.

How fast self-discharge in a battery occurs is dependent on the type of battery, state of charge, charging current, ambient temperature and other factors. Primary batteries are not designed for recharging between manufacturing and use, and thus to be practical they must have much lower self-discharge rates than older types of secondary cells. Later, secondary cells with similar very low self-discharge rates were developed, like low-self-discharge nickel–metal hydride cells.