Batteries ohmic overvoltage

Ohmic Overvoltage Overvoltage caused by the ohmic drop in an electrolyte. On-Load Voltage The difference in voltage between the terminals of a cell or battery when it is discharging. 

The main component of voltaic inefficiency is usually the ohmic loss, compounded by mass-transport-related overvoltage. The extent of coulombic losses depends on the system and may be due to parasitic electrode and/or chemical reactions, self-discharge, and/or shunt currents (in flowing systems wth a common electrolyte). The efficiency, as measured at battery terminals differs from the effective value if a part of the battery s energy is used to operate auxiliaries (e.g., pumps) or if thermal losses are involved (high-temperature batteries). 

The so-determined Ri comprises ohmic resistance within the electrodes and the electrolyte as well as overvoltage at the phase boundaries between the electrodes and the electrolyte. Equation (56) implies that the overvoltage is comparatively small compared to the ohmic voltage drop. To ensure a certain comparability, the tests are specified for many types of batteries and cell sizes (examples in Ref. 5). 

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