Restladung

Restladung, or residual charge, is the non-zero electric charge that remains on a conductor or dielectric after a discharge event, or in a system with ongoing electric fields. In electrostatics and electronics, it can arise from incomplete discharge, dielectric absorption, surface charges, or leakage currents through insulation. The amount and persistence depend on factors such as material permittivity, geometry, humidity, temperature, and the presence of conductive paths. In measurement and high-impedance circuitry, rest charge can introduce offset voltages, stray electric fields, or attraction and repulsion forces; it is typically reduced by grounding, discharge through a known resistor, shielding, or controlled equalization.

In capacitors and dielectric materials, dielectric absorption can cause the so-called memory or rest charge effect: after a voltage is removed, a portion of the charge remains temporarily in the dielectric, slowly releasing and causing a rising voltage on the terminals. In battery technology, the term rest charge is sometimes used to describe the open-circuit voltage of a cell after a rest period, which reflects the state of charge more than the loaded voltage. This rest voltage is temperature dependent and may drift with age; manufacturers use it to estimate state of charge and to assess state of health.

Restladung is therefore a general concept used in multiple fields to describe residual electrostatic content that can affect measurements, safety, and performance.