The reduction of the voltage of a battery when it is not in use.
Charging or discharging always takes place in a battery, and the underlying chemical processes cannot be switched off completely. This means that a battery constantly loses voltage.
The higher the ambient temperature, the higher the self-discharge. In addition, a battery can also lose charge through connected silent loads while a vehicle is not in use.
To compensate for self-discharge, trickle charging can be used, e.g., for batteries that are to remain in continuous operation.