Battery (All): Terminology: Short-Circuit
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A short-circuit is when the current takes a short cut where the resistance is less and therefore does not go via the intended route. A short-circuit can be caused for example by particles detaching from the plates in the cells. Eventually these deposits can be so large that a conductive connection is made between the two plates so that the current can flow between the two plates instead. A short-circuit in a cell can fully discharge a battery and render the battery useless.