Main Operative Parameters of Batteries

The voltage drop observed in 5.10, typically 0.02-0.03 V, at the beginning of discharge, is related to the delay of the anodic discharge reaction (see Sect. 5.3.2), due to the electrolyte saturation with lead ions. 

The operative working condition of a battery can be represented by simple equivalent circuits, which are only valid for charging or discharging operations without considering the current transient phenomena. The discharging equivalent circuit of a battery is shown in Fig. 5.11. 

In this case, the battery is represented by a fixed voltage connected in series with a resistance Zfi. The voltage Vbatt at the terminals of the battery is different from the open circuit voltage Eq, because of the drop in voltage caused by the internal resistance Zfi. Thus, if / is the current flowing out of the battery, as shown in Fig. 5.11, the terminal voltage of the battery is expressed by the following equation  

If I — 0, obviously the terminal voltage equals the open circuit voltage  

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