*3.3. Open Circuit*

The failure mode Open Circuit can be caused by broken connections at various parts of the battery. The electrical connection between the battery terminal and the connected cell can break due to massive mechanical impact from outside the battery housing and especially the battery terminals. As a result, the battery directly loses its full performance capability. Since many battery housings do not have terminal niches and the battery terminals are exposed, they are probably very prone to unintentional mechanical influences from the outside. This can lead to more frequent occurrences of *Open Circuit*, whereas

terminal niche may protect the battery terminal from careless handling and prevent frequent *Open Circuit*. The individual cells of the lead battery are electrically contacted internally via solid inter-cell connectors to connect the six individual cells to one battery. If one of these inter-cell connectors between the cells breaks, there is also an *Open Circuit*. Finally, within each of the six individual cells, there are connections from the positive and negative electrodes to the respective inter-cell connector. These partial elements of the electrodes, known as electrode lugs, can break as well and thus make this electrode inactive. However, this means that only one part of a cell and thus one part of its capacity is no longer available; the remaining electrodes and cells work as usual. Due to the failure of *Open Circuit* the battery can lose its entire performance, as its circuit is interrupted. The *Open Circuit* happens suddenly without prior indication and thus is not detectable. Consequently it is allocated to the sudden faults and clearly defined by BCI with *Open Circuit*.
