 Battery self-discharge

Battery self-discharge is loss of recoverable stored charge through internal processes while a battery supplies no useful external electric current. Parasitic reactions and internal leakage can change the charged state even when the external terminals are open.

A storage experiment compares recoverable capacity after controlled waiting intervals with an otherwise identical freshly charged or prepared cell. Holding temperature and subsequent discharge conditions fixed separates storage loss from a changed capacity test. Terminal voltage alone need not measure the lost capacity, because voltage also depends on chemistry and relaxation. Self-discharge is distinct from the intentional current drawn by a connected sleeping device.